DEPJ 


No. 


APPLIED    PHYSIOLOGY 


INCLUDING 


THE   EFFECTS    OF   ALCOHOL 
AND   NARCOTICS 


BY 

FRANK   OVERTON,    A.M.,  M.D. 

LATE  HOUSE  SURGEON  TO  THE  CITY  HOSPITAL,  NEW  YORK 


INTERMEDIATE  GRADE 


NEW  YORK- :-CINCINN ATI- :•  CHICAGO 

AMERICAN    BOOK    COMPANY 


09 


COPYRIGHT,  1897,  BY 
AMERICAN  BOOK  COMPANY 


APPLIED   PHYSIOLOGY 


EDUCTION  DEPT. 


(Ld 


PREFACE 

THE  author  of  this  intermediate  grade  of  Applied  Physi- 
ology has  designed  the  work  to  be  not  merely  an  intro- 
duction to  the  study  of  anatomy  and  physiology,  but  a 
complete  elementary  work  in  itself,  giving  a  clear  picture 
of  how  each  organ  of  the  body  performs  its  work. 

In  presenting  hygienic  facts  to  pupils  before  they 
have  an  elementary  knowledge  of  anatomy  and  physiology, 
there  is  a  violation  of  pedagogical  principles.  The  laws 
of  healthful  living  cannot  be  grasped  without  this  elemen- 
tary knowledge  of  the  human  machine  to  which  the  laws 
apply.  Advice  to  a  pupil  will  have  an  effect  in  direct  pro- 
portion to  the  confidence  reposed  in  the  teacher.  New 
environments  and  duties  demand  new  applications  of  laws. 
Every  business  man  is  often  compelled  to  break  common 
hygienic  laws  in  regard  to  eating,  exposure,  and  overwork. 
Thus  mere  advising  conduces  but  little  toward  intelligent 
living.  On  the  other  hand,  prohibition  arouses  in  children 
a  desire  to  do  the  forbidden  thing,  especially  if  it  be  a  rule 
insisted  upon  at  school.  Moreover,  the  unavoidable  incon- 
sistencies of  teachers  themselves  will  upset  the  pupil's 
confidence  in  all  laws.  For  these  reasons  dogmatic  hygi- 
enic advice  is  avoided,  but  anatomical  and  physiological 
facts  are  simply  stated  and  developed. 

By  way  of  example,  however,  it  has  seemed  wise  to  indi- 
cate detailed  hygienic  applications  of  physiology  and  anat- 
omy along  a  single  line,  leaving  it  to  teachers  to  apply  the 
same  principles  to  other  abuses  of  the  body  in  answer  to 


4  PREFACE 

the  numerous  questions  which  every  class  will  undoubtedly 
ask.  For  this  purpose  the  subject  of  alcohol  and  tobacco 
has  been  selected,  both  because  of  their  wide-spread  abuse, 
and  also  because  of  their  universal  effect  upon  all  parts 
of  the  body.  In  this  way  the  pupil  will  be  made  to  realize 
the  wide-spread  results  of  abusing  even  a  single  part  of 
the  body.  Great  care  has  been  exercised  to  make  the  dis- 
cussion of  stimulants  and  narcotics  correct  in  every  par- 
ticular, and  to  bring  it  fully  into  conformity  with  the  most 
recent  temperance  legislation. 

The  cuts  are  mostly  selected  from  the  author's  advanced 
work,  but  a  few  original  ones  have  been  added.  The 
microscopic  appearances  of  tissues  have  been  especially 
emphasized. 

Practical  demonstrations  have  been  omitted ;  for,  without 
explanations,  they  are  meaningless  to  pupils  of  the  inter- 
mediate grades.  Yet,  without  demonstrations  the  intelli- 
gent study  of  unfamiliar  parts  is  impossible.  Teachers 
will  find  an  outline  of  a  complete,  yet  simple,  series  of 
experiments  in  the  author's  advanced  work. 

With  the  desire  to  supply  a  long-felt  want,  the  author 
presents  these  results  of  experience  and  thought  to  teach- 
ers and  pupils. 

PATCHOGUE,  N.Y. 


CONTENTS 


I.   CELLS      .        .        .        .        .'       .        .  .  .  .        7 

II.   DIGESTION       .        .        .        .        «•'       .  .  .  15 

III.  FOODS      .        .        .,       .        .        .        ,  .  .  .      26 

IV.  INTEMPERANCE  AND  POISONS          .        i  .  .  .      35 
V.   TOBACCO          .        .        .        .        .        .  .  .  .      44 

VI.   ALCOHOL         .        .        .        .        .,        .  ,  "„  j.      49 

VII.   THE  BLOOD  AND  ITS  CIRCULATION       -.  .  .  .      60 

VIII.   BLEEDING,  WOUNDS,  AND  DISEASE  GERMS  .  -  -.  .     .      72 

IX.   RESPIRATION            .        .        ...  .  .  '   .      80 

X.  VENTILATION,  HEAT,  AND  CLOTHING      .  .  .  .      92 

XI.   THE  SKIN  AND  KIDNEYS 104 

XII.   THE  NERVES  AND  SPINAL  CORD            .  .  .  .114 

XIII.  THE  BRAIN     .       ....        .        .        .  .  .  .122 

XIV.  NARCOTICS  AND  THE  NERVOUS  SYSTEM  .  .  .     132 
XV.  THE  SENSES            .        .       '.        .        .  .  .  .143 

XVI.   BONES    ..        .        .,       .        .,..'.  .  .     155 

XVII.   MUSCLES         .        .        .        .        .        .  .  .  .165 

GLOSSARY           .        .      ';        ..      *        .        .  ,  v  .  .     175 

INDEX ,  .  .  .183 


APPLIED   PHYSIOLOGY 


CHAPTER   I 
CELLS 

1.  The  ameba.  —  In  moist  earth  there  lives  a  little  ani- 
mal called  the  ameba.  It  is  so  small  that  you  cannot  see 
it  without  a  magnifying  glass  many  times  as  strong  as  the 
best  spectacles.  When  you  do  see  it  you  will  not  know 
that  it  is  an  animal,  for  it  has  neither  eyes,  nor  head,  nor 
arms,  nor  legs.  It  is  simply  like  a  lump  of  jelly.  But  if 
you  look  a  minute,  you  will  see  it  put  forth  some  part  of 
its  body  like  a  finger  to  take  a  little  lump  of  food.  This 
finger  is  also  a  mouth  and  swallows  the  food.  Then  the 


An  ameba,  sketched  at  intervals  of  ten  seconds  ( x  400) . 

finger  becomes  a  stomach  and  changes  the  food  to  blood 
so  that  the  animal  can  grow.  When  it  wants  to  go  for  a 
walk,  it  puts  forth  a  finger,  and  then  the  whole  body  rolls 
itself  into  the  finger,  and  thus  it  moves  forward.  So  the 
little  ameba  can  make  an  arm,  or  a  mouth,  or  a  stomach, 
or  a  leg,  wherever  and  whenever  it  wants  to. 

7 


IV 


,1  .r 'APPLIED   PHYSIOLOGY 


An  animal  that  can  make  any  part  of  its  body  anew  to 
suit  itself  should  be  very  prosperous  and  happy.  In  fact, 
the  ameba  does  grow  so  fast  that  in  a  day  or  two  it  thinks 
itself  big  enough  to  become  two  animals,  and  so  it  splits 
itself  into  two  parts,  and  each  half  goes  off  by  itself  as  a 
full-grown  ameba. 

2.  Cells.  —  Man  has  a   separate  part  of  the  body  set 
aside  to  do  each  kind  of  work.     He  has  legs  which  carry 
him  to  his  food,  and  arms  with  which  to  get  the  food,  and 
a  mouth  with  which  to  eat  it.     But  these  parts  do  not 

make  the  real  man,  for 
some  men  lose  their  arms 
and  legs  and  yet  remain 
men.  The  real  man  is  the 
mind  which  lives  in  the 
body  and  makes  the  arms, 
and  legs,  and  mouth  do  as 
it  wants  them  to  do.  But 
a  man's  arm  or  his  leg,  or 
any  other  part  of  his  body, 
is  itself  made  of  millions 
of  little  living  things  like 
the  ameba.  We  call  each 
of  these  living  things  a  cell.  Some  of  these  cells  are 
long,  some  flat,  and  some  of  other  shapes.  Each  has 
the  form  best  fitted  for  the  work  it  does,  but  all  are  ex- 
ceedingly small.  They  are  held  in  place  by  fine  strings 
called  connective  tissue.  By  scraping  the  skin,  cells  can 
be  removed  from  its  surface.  They  look  like  flour. 

3.  Mind  rules  the  cells.  —  The  mind   takes  good  care 
of  these  cells.     When  we  eat  we  feed  the  cells,  and  we 
breathe  so  that  each  cell  can  get  a  little  air.     To  repay  the 
mind  for  its  care  the  cells  all  work  together  like  good  ser- 


Cells  from  the  human  body  (X  200). 

a  A  colored  cell  from  the  eye. 

b  A  white  blood  cell. 

c  A  connective  tissue  cell. 

d  A  cell  from  the  lining  of  the  mouth. 

e  Liver  cells. 

/  A  muscle  cell  from  the  intestine. 


CELLS  9 

vants  to  do  just  as  the  mind  tells  them.  Thus,  when  the 
mind  wants  to  walk,  all  the  cells  of  the  legs  get  themselves 
under  the  body  and  push  the  body  ahead.  They  do  it  so 
willingly  that  we  do  not  think  how  hard  they  have  to 
work.  When  the  mind  wishes  to  stop,  it  tells  the  cells  of 
the  legs  that  they  need  not  work  any  more  until  it  wishes 
to  move  again. 

Sometimes  it  is  very  hard  for  the  mind  to  teach  the  cells 
to  work  just  as  they  should  and  to  keep  still  when  they 
ought.  Boys  and  girls  go  to  school  so  that  they  may  learn 
how  to  make  the  cells  obey  the  mind.  We  ought  to  take 


Water,  12  gallons 


Albumin  or  gelatine,  20  Ib. 
Substances  of  which  the  body  is  composed. 


Fat.  10  Ib. 


good  care  of  our  bodies  because  the  living  cells  of  which 
they  are  composed  make  such  good  servants  for  the  mind. 

4.  Of  what  the  cells  are  made:   water.  —  About   three 
fourths  of  each  cell  of  the  body  is  water.     Water  is  found 
even  in  teeth  and  in  bone.     All  animals  must  have  water 
to  drink.     Even  the  driest  food,  like  crackers,  has  a  great 
deal  of  water,  while  other  kinds,  like  meat  and  potatoes, 
are  nearly  three  fourths  water.     In  all,  a  man   swallows 
two  or  three  quarts  of  water  each  day. 

5.  Albumin.  —  Next  to  water  something  which  is  like 


IO 


APPLIED   PHYSIOLOGY 


the  white  of  an  egg  forms  the  most  of  the  body.  This 
substance  is  called  albumin,  because  when  boiled  it  be- 
comes white  and  hard.  It  is  the  living  part  of  cells  and 
must  be  eaten  to  sustain  their  life.  It  is  found  in  all  food, 
both  animal  and  vegetable.  We  eat  about  four  and  a  half 
ounces  of  albumin  each  day. 

6.  Fat  —  Oil,  or  fat,  is  found  in  little  pockets  between 
the  cells.     It  is  in  a  liquid  form,  and  becomes  hard  only 

when  the  body  cools 
after  death.  When  we 
boil  a  piece  of  meat,  the 
pockets  are  softened  so 
that  the  fat  runs  out  and 
floats  upon  the  top  of 
the  water.  Fat  must  be 
eaten  in  order  that  the 
cells  of  the  body  may 
be  healthy,  but  they  can 
live  for  a  long  time  with- 
out it,  for  the  fat  of  the 
body  is  made  out  of  albumin,  and  not  from  the  fat  which 
is  eaten.  The  fat  around  the  cells  is  like  a  cushion  which 
protects  the  cells  and  keeps  them  warm.  It  also  makes 
the  body  round  and  handsome.  Fat  is  found  in  all  com- 
mon food.  We  eat  about  three  ounces  each  day. 

7.  Starch  and  sugar.  —  Starch  and  sugar  also  enter  the 
body  as  food.     Only  a  little  of  these  is  really  found  in  the 
body  at  once,  for  it  is  soon  used  up  in  warming  the  body. 
Starch  is  found  in  all  vegetable  food  in  the  form  of  small 
grains.     Cooking  in  hot  water  makes  these  grains  swell 
and   burst.      Then   they   dissolve    in   water   and   form   a 
paste.     In  the  young  plant  there  is  but  little  sugar  and 
a  great  deal  of  starch,  but  when  the  plant  ripens,  the 


Fat  tissue  (x  100). 

Connective  tissue  cells  form  pockets  in  which 
the  liquid  fat  is  stored. 


CELLS  I I 

starch  changes  to  sugar.     When  starch  is  eaten,  it  is  also 
changed  to  sugar.     So  starch  and  sugar  are  the  same  kind 
of   food.      About   one 
quarter  of  a  pound  of 
starch   or   sugar   must 
be  eaten  each  day. 

8.  Minerals.  —  In 
the  body  there  are  also 
minerals,  such  as  lime, 

iron,  potash,  and  salt.  starch  grains  (x  400). 

When     the     body     is     l§r  a,  of  potato.  b,  of  corn, 

burned,  these  are  left 

behind  as  ashes.  The  lime  stiffens  the  bones.  Iron  is 
found  in  the  blood  and  coloring  matter  of  the  body. 
Potash  and  salt  are  found  all  through  the  body.  These 
minerals  are  found  in  all  food,  for  all  leave  ashes  when 
burned.  Yet  some  salt  must  be  added  to  food. 

9.  Food.  —  Everything  which  makes  the  cells  and  fluids 
of  the  body  is  composed  of  either  water,   albumin,  fat, 
sugar,  or  minerals.     These  sustain  life,  and  are,  foods.     All 
other  kinds  of  substances  are  harmful  or  poisonous. 

10.  Oxidation.  —  All  kinds  of  food  are  constantly  being 
eaten,  and  yet  only  water  and  mineral  substances  leave 
the  body  in  anything  like  the  form  in  which  they  entered. 
What  becomes  of  the  rest  ? 

When  a  piece  of  meat  is  put  into  a  hot  fire,  it  bursts 
into  a  flame  and  burns  to  smoke  and  ashes.  By  its  burn- 
ing it  gives  off  heat,  and  makes  the  fire  hotter.  If  the 
draft  of  the  stove  is  closed  tightly,  the  fire  does  not  burn, 
for  a  stream  of  air  must  flow  steadily  into  the  fire.  The 
air  is  one  fifth  oxygen  gas.  This  oxygen  unites  with  the 
meat  and  forms  two  invisible  gases  —  carbonic  acid  gas 
and  vapor  of  water.  These  gases  are  the  smoke.  The 


12 


APPLIED   PHYSIOLOGY 


ashes  are  the  mineral  parts  of  the  meat.  This  is  what 
takes  place  in  every  fire.  We  call  it  oxidation.  If  the 
fire  is  under  the  boiler  of  an  engine,  the  heat  is  used  in 
changing  the  water  to  steam.  The  steam  can  then  be 
made  to  do  work. 

11.  Oxidation  within  the  body.  —  Besides  meat  and  other 
kinds  of  food,  air  is  also  taken  inside  of  our  bodies.    Car- 
bonic acid  gas  and  water  are  given  off  in  the  breath,  our 

bodies  are  warmed,  and 
they  perform  work,  as  a 
steam  engine  does.  The 
body  is  really  an  engine 
directed  by  the  mind.  The 
lungs  are  the  boilers,  while 
the  nose  is  the  draft  where 
the  oxygen  enters  and  the 
carbonic  acid  gas  and 
water  pass  out.  Both  the 
food  and  the  cells  of  the 
body  are  oxidized.  By  the 
oxidation  the  same  heat  is 
produced  as  though  the  food  were  burned  outside  the  body, 
but  it  occurs  so  slowly  that  no  flame  is  produced.  Most 
of  the  heat  simply  warms  the  body.  The  muscles  and 
brain  form  the  engine  which  changes  the  rest  of  the  heat 
to  work.  All  the  power  of  a  man's  body  is  derived  from 
the  heat  of  oxidation.  Running,  speaking,  and  thinking 
are  different  kinds  of  work,  and  depend  upon  the  heat  of 
oxidation  for  power.  v 

12.  Use  of  food.  —  The  greater  part  of  the  fuel  for  oxi- 
dation is  supplied  by  the  food  before  it  reaches  the  cells 
of  the  body.    The  cells  themselves  are  also  slowly  oxidized. 
In  course  of  time  their  substance  is  completely  burned  up, 


Diagram  of  burning  or  oxidation  in  a 
stove. 


CELLS 


and  its  place  supplied  by  new  food.  So  the  object  in  tak- 
ing food  is  both  to  supply  the  cells  with  what  was  burned 
from  them,  and  also  to  furnish  fuel  for  the  greater  part  of 
the  oxidation  within  the  body. 

Water  and  mineral  substances  are  not  oxidized,  but  only 
add  weight  to  the  cells  of  the  body.  Fat  and  starch  give 
only  heat.  Albumin  gives  both  weight  and  heat,  for  it 
both  becomes  a  part  of 
the  living  cells  and  also 
is  oxidized.  So  anything 
which  gives  either  weight 
or  heat  to  the  body  is 
food, 

13.  Relation  of  plants 
to  animals.  —  Man's  food 
comes  both  from  animals 
and  from  vegetables,  but 
animals  feed  upon  vege- 
tables, or  else  eat  -other 
animals  which  eat  vege- 
tables. Vegetables  feed 
upon  substances  in  the 
soil  and  air.  The  burned-  Diagram  of  the  restoration  of  oxygen  to 
up  parts  of  man  and  ani-  tne  air  after  oxidation,  and  of  the  rebuild- 
ing of  burned  material  into  living  forms. 

mals  go  back  to  the  soil 

and  air  and  become  food  for  plants.  Thus  plants  build 
the  burned  products  of  man's  body  into  food,  which  can 
be  used  once  more  by  man.  So  year  after  year  the 
food  makes  the  round  from  the  soil  to  the  plants,  and  then 
to  animals  and  man,  and  back  again  to  the  soil.  A  plant 
lives  on  the  soil  a*nd  air.  An  animal  cannot  live  on  these, 
but  must  eat  what  plants  have  formed  from  them.  This 
makes  the  real  difference  between  plants  and  animals. 


Carbonic  Acid  Gas 

in  the  air  going 

into  the  tea/ 


14  APPLIED  PHYSIOLOGY 

SUMMARY 

1.  The  body  is  made  of  separate  living  cells,  each  like  a 

little  animal. 

2.  Each  cell  obeys  the  mind  and  works  for  the  benefit  of 

the  body. 

3.  Cells  are  made  of  five  things ;  viz.,  water,  albumin,  fat, 

starch,  or  sugar,  and  mineral  substances. 

4.  These  five  substances  are  formed  outside  the  body,  and 

are  food  for  man. 

5.  Oxygen  is  also  taken  inside  the  body,  and  burns  up  or 

oxidizes  the  food  and  some  of  the  substances  of  the 
cells. 

6.  By  the  oxidation  within  the  body  heat  is  produced. 

7.  The  cells  of  the  body  form  an  engine  which  changes 

some  of  the  heat  to  work. 

8.  What  we  eat  either  is  added  to  the  cells  of  the  body,  or 

else  is  oxidized  to  produce  heat  and  work. 

9.  Food  is  anything  which,  when  swallowed,  gives  weight 

or  heat  to  the  body. 


CHAPTER   II 

DIGESTION 

14.  Digestion.  —  We  have  seen  how  the  little  amebas  can 
take  food  into  any  part  of  their  bodies,  and  then  can  change 
it  so  that  it  becomes  a  living  part  of  themselves.     Each 
ameba  has  to  seek  its  own  food,  and  to  take  it  just  as  it 
is  found.      The  cells  of  our  bodies  have  their  food  pre- 
pared for  use  and  brought  to  them  by  a  few  of  the  cells 
of  the  body  set  aside  for  that  special  work.     This  food  is 
the  blood.     All  food  eaten  must  become  a  part  of  the  blood 
before  it  can  nourish  the  body. 

The  preparation  of  food  so  that  the  cells  can  use  it  is  f 
called  digestion.      The  object  of  digestion  is  to  separate 
food  from  its  hard  and  waste  parts,  and  then  to  soften 
and  dissolve  it  so  that  it  becomes  a  liquid  and  can  flow 
with  the  blood. 

15.  Cooking.  —  Man  usually  begins  digestion  outside  of 
his  body  by  cutting  his  food  into  pieces  and  heating  or 
cooking  it.    By  cooking  most  kinds  of  albumin  are  changed 
to  a  jelly  like  or  solid  form,  like  a  cooked  egg,  but  some 
kinds,  like  the  connective  tissue  which  binds  the  cells  to- 
gether, are  softened.     Cooking  should  leave  food  so  soft 
that  it  can  be  chewed  easily.     Usually  the  longer  food  is 
cooked,  the  softer  it  becomes. 

Cooking  softens  starch  grains  and  causes  them  to  swell 
and  burst,  and  finally  to  dissolve  in  water,  forming  a  thin 
paste.  Man  cannot  digest  raw  starch,  and  so  it  must  be 

15 


1 6  APPLIED   PHYSIOLOGY 

cooked  if  it  is  to  be  of  any  use  to  his  body.  Cooking 
does  not  change  sugar. 

Cooking  simply  melts  fat,  but  does  not  change  it,  unless 
the  heat  is  great  enough  to  burn  it.  But  in  meat  and 
vegetables,  cooking  softens  the  pockets  of  albumin  in  which 
the  fat  is  stored,  and  sets  it  free,  so  that  it  floats  upon  the 
water.  In  this  way  pure  lard  and  tallow  are  made. 

Cooking  develops  the  taste  of  food  so  that  it  is  more 
agreeable  to  the  body.  It  also  destroys  many  poisons  in 
food. 

16.  Ways  of  cooking.  —  Man  applies  heat  in  cooking  in 
three  ways.     He  boils  the  food  in  water,  or  surrounds  it 
with  heat  in  a  hot  oven,  or  exposes  one  side  at  once  to  the 
heat,  as  in  broiling.     It  makes  little  difference  how  it  is 
done,  so  long  as  it  is  done  well.     Cooked  food  should  taste 
good  and  be  either  soft,  or  else  brittle,  so  that  it  can  be 
chewed  fine.     If  food  is  tough  or  doughy,  so  that  it  cannot 
be  chewed  well,  it  is  surely  not  well  cooked. 

After  the  food  is  cooked  we  put  it  upon  a  plate  and  cut 
it  into  fine  bits.  This  saves  the  mouth  a  great  deal  of 
work  and  keeps  us  from  eating  too  fast.  Every  one  should 
take  time  to  cut  his  food  into  small  pieces  before  eating  it. 

17.  Mouth  digestion.  —  After  the  food   is  cooked,  man 
takes  it  into  his  mouth,  and  there  continues  its  digestion 
by  grinding  it  between  his  teeth  and  rolling  it  about  with 
his  tongue  and  cheeks,  until  it  is  in  fine  particles.     At  the 
same  time  he  mixes  it  with  a  watery  fluid  so  that  it  is  like 
a  thin  paste. 

18.  The  teeth.  —  The  teeth  are  bony  pegs  set  into  the 
jaw  bones.     Those  in  the  front  part  of  each  bone  are 
sharp  in  order  to  bite  off  lumps  of  food.       Those  in  the 
back  part  of  the  mouth  are  flat  so  as  to  grind  the  food  to 
pieces.      Between   the  ages  of  six  and  thirteen   years  a 


DIGESTION 


A  tooth  cut  open. 

a  enamel. 

b  dentine  or  bone. 

c  pulp  cavity  con- 
taining blood 
tubes  and 
nerves. 

d  cement. 


child  loses  his  first  set  of  teeth  and  gets  a  whole  new  set 
with  eight  additional  ones. 

19.  Structure  of  teeth.  —  Through  the  center  of   each 
tooth  there  runs  a  small  tube  which  contains  a  nerve  and  a 
blood  tube.     The  outside  of  the  part  above 

the  jaw  is  covered  with  a  very  hard  sub- 
stance called  enamel,  which  protects  the 
inner  part  from  decay  and  injury.  Biting 
hard  things,  like  nuts  or  wood,  often  breaks 
the  enamel,  and  then  the  tooth  decays. 
When  the  decay  reaches  the  nerve,  the 
tooth  aches  and  becomes  very  tender. 

20.  Care    of    the    teeth.  —  Bits   of   food 
sometimes  get  between  the  teeth,  and  if  left 
there  make  the  breath  smell  bad,  and  often 
cause  the  teeth  to  decay.     A  wooden  tooth- 
pick used  after  each  meal  will  best  remove 
these  bits  of  food. 

A  gray  substance,  called  tartar,  often  collects  upon  the 
teeth,  making  them  rough  and  dirty.     One  should  keep 
this  from  forming  by  brushing  the  teeth  with  a  tooth- 
brush and  water  each  morning  and  night.     Tobacco-chew-  \ 
ing  stains  the  teeth  almost  black  and  causes  them  to  decay/ 
quickly.  * 

21.  The  jaws.  —  The  upper  jaw  is  a  part  of  the  bone  of 
the  face  and  cannot  be  moved.     The  lower  jaw  is  a  half 
circle  of  bone  with  its  two  back  ends  turned  up.     It  can 
be  moved  up  and  down,  forward  and  backward,  and  side- 
wise.     By  its  movements  it  causes  the  teeth  to  act  upon 
the  food  in  every  direction. 

22.  The  cheeks  and  tongue.  —  The  cheeks  and  tongue 
are  made  up  mostly  of  muscles  which  can  roll  the  food 
about  in  any  direction.     They  have  a  fine  sense  of  feeling, 

ov.  PHYSIOL.  (INTER.)  —  2 


18 


APPLIED   PHYSIOLOGY 


so  as  to  be  able  to  judge  of  the  position  of  the  food  and  to 

tell  when  it  is  chewed  enough. 

23.    Mucous  membrane.  —  The  mouth,  as  well  as  every 

other  cavity  of  the  body, 
a  has  a  thin  lining  called 
mucous  membrane,  which 
looks  like  a  fine,  soft  skin. 
At  the  lips,  nose,  and  other 
openings,  this  lining  joins 
the  skin  so  that  it  is  im- 
possible to  tell  where  the 
one  begins  and  the  other 
ends.  It  is  really  a  part 
of  the  skin  turned  inside 
the  body.  Mucous  mem- 
brane is  made  of  a  net- 
work of  cells  and  fibers, 
which  is  covered  with  an 
unbroken  layer  of  firm 
cells  called  egithelimn.  __ 
24.  Glands.  —  In  each 
mucous  membrane  are 
tiny  tubes  which  open 
upon  its  surface.  Each 
tube  is  lined  with  cells 

b  the  epithelium  continued  into  a  simple  tube,    of    epithelium    like    those 
c  the    epithelium    continued    into   a   simple  '     .  r  r       , 

pOCkeL  upon  the  surface  of  the 

d  the  epithelium  continued  into  a  series  of    membrane.  The      Cells 

branching  tubes  and  pockets.  . .    .  ,          ,  , 

».  c,  and  d  are  glands.  lmmg  each  tube  produce 

a     slightly     slimy     fluid 

called   *ui(fue       They  pour  just  enough  of  it  upon  the 
surface  of  the  membrane  to  moisten  it. 

A  tube  or  collection  of  tubes  whose  cells  can  form  a 


Diagram  of  glands. 

the  surface  of  a  mucous 


DIGESTION 


mous  supply  of  a  substance  is  called  a  gland.  All 
mucous  membranes  contain  enough  mucous  glands  to 
keep  their  surfaces  moist.  In  addition  some  mucous 
membranes  also  contain  glands  which  produce  other  sub- 
stances. 

25.  Salivary  glands.  —  Upon  the  sides  of  the  mouth  are 
the  openings  of  several  small  tubes  through  which  a  fluid 
called  the  saliva  is  always  enter- 
ing to  moisten  the  mouth.    While 

one  is  eating,  more  saliva  flows, 
so  that  Qver  a  quart  is  produced 
each  day.  Each  tube  runs  deep 
into  the  cheeks  and  suddenly 
divides  again  and  again  like  the 
branches  of  a  tree,  so  that  the 
finest  tubes  cannot  be  seen  with- 
out a  microscope.  Each  tube 
is  made  of  cells  set  edge  to  edge. 
These  cells  produce  the  §aliva_ 
from  th^  Moor! 

Each  bunch  of  tubes  is  rolled 
together,  forming  a  mass  about  the  size  of  a  walnut.  Each 
mass  is  called  a  salivary  gland.  There  is  a  salivary  gland 
in  front  of  each  ear,  and  two  under  each  side  of  the  jaw. 
In  mumps  these  glands  swell  and  produce  lumps  around 
the  lower  jaw. 

26.  The  saliva.  —  The  saliva  is  a  watery  fluid  which 
flows  very  freely  when  anything  is  chewed.     Saliva  has  a 
little  power  to  change  starch  to  sugar,  but  its  main  use  is 
to  dissolve  the  food  into  a  thin  paste  which  can  be  swal- 
lowed.    The  food  should  always  be  chewed  so  long  as  any 
lumps  can  be  felt. 

27.  The  pharynx  and  swallowing.  —  When  the  food  has 


A  salivary  gland  ( X  200). 

a  tube  of  epithelium  forming  the 
gland,  cut  lengthwise. 

b  tubes  cut  crosswise. 

c  connective  tissue  binding  the 
tubes  in  place. 


2O 


APPLIED   PHYSIOLOGY 


been  chewed  to  a  paste,  it  is  collected  into  a  mass  upon 
the  back  of  the  tongue,  and  pushed  into  a  muscular  bag 
called  the  pharynx.  The  pharynx  has  seven  openings. 
Two  into  the  nose  and  two  into  the  ears  can  be  closed  by 
raising  the  back  part  of  the  roof  of  the  mouth.  An  open- 
ing into  the  windpipe 
can  be  closed  by  a  cover 
called  the  e^lottis.  The 
opening  into  the  mouth 
can  be  closed  by  two 
curtains,  which  slide 
across  the  back  of  the 
tongue  and  meet  in  the 
middle.  The  opening 
into  the  tube  leading  to 
the  stomach  is  the  only 
one  left.  When  food 
reaches  the  pharynx,  its 
muscles  squeeze  the  food 
into  the  open  tube  lead- 
ing to  the  stomach. 
Thus  food  is  swallowed. 
28.  The  esophagus.  — 
The  tube  leading  from 
the  pharynx  to  the  stom- 
ach is  called  the  esoph- 
agus. The  esophagus 
that  it  is  forced  in  the  direction 
of  water  in  a  horse's 


Diagram  of  the  beginning  of  swallowing. 

a  top  of  tongue. 

b  pharynx. 

c  morsel  of  food. 

d  sliding  door  of  the  front  of  the  pharynx. 

e  soft  palate. 

/  epiglottis. 


squeezes  the  food  so 

of   the   stomach.     Each    swallow 

esophagus  can  be  seen  to  run  up  its  neck  on  its  way  to  the 

stomach.    Man's  esophagus  would  look  the  same  if  it  were 

near  the  surface. 

29.   The  stomach.  —  The  inside  of  the  body  is  divided 


DIGESTION 


21 


into  two  parts  by  a  sheet  of  muscle  called  the  diaphragm. 

The  upper  part  is  called  the  chest  or  thorax,  and  holds  the 

esophagus,  lungs,  and  heart.     The  lower  part  is  called  the 

abdomen,  and  holds  the  stomach,  intestine,  liver,  pancreas, 

and  kidneys.     The  stomach  is  a  thin  bag  of  muscle  lying 

upon    the    left   side   of 

the  body,  just  under  the 

lowest  ribs.     It  is  lined 

with  mucous  membrane, 

which      contains      very 

small      tubes.        These 

tubes  are  glands  which 

produce    a   fluid    called 

the  gastric  juice.     The 

stomach    squeezes    and 

stirs  the  food  about  in 

a    gentle    manner,    and 

mixes  it  with  the  gastric 

juice,    so    that    in    the 

course  of  an  hour  or  two 

the  food  is  ground  and 

mixed,  much  as  it  was 

in  the  mouth. 

30.  The  gastric  juice. 
—  The  glands  produce 
about  three  quarts  of 
gastric  juice  daily.  It 
is  mostly  water,  but  it 
contains  a  small  amount 
of  a  sour  substance  called  hydrochloric  acid,  and  of  a  white 
substance  called  pepsin.  These  two  substances  eat  away 
or  dissolve  albumin,  so  that  it  becomes  soft,  and  finally 
fully  dissolves  in  the  water  of  the  gastric  juice.  Digested 


Diagram  of  second  part  of  swallowing. 

a  top  of  tongue  arched  backward  and  up- 
ward. 

b  pharynx. 

c  morsel  of  food  pushed  into  the  pharynx  by 
the  back  of  the  tongue. 

d  sliding  doors  of  the  pharynx  which  have 
come  together  in  the  middle. 

e  soft  palate  lifted  upward  to  shut  off  the  nose. 

/  epiglottis  folded  downward  to  close  the 
larynx. 


22 


APPLIED   PHYSIOLOGY 


Organs  of  the  chest  and  abdomen. 

a  lungs.  d  stomach. 


albumin   is   called  peptone.     The   stomach  has  no  effect 
upon  starch  or  fat.     Only  a  small  amount  of  the  albumin 

is  really  changed  to  peptone  by 
the  gastric  juice,  for  every  few 
moments  the  opening  leading 
from  the  stomach  permits  a 
small  quantity  of  food  to  pass 
out.  So  food  does  not  remain 
with  the  gastric  juice  long 
enough  to  be  fully  digested. 
The  mixture  of  food  and  gastric 
juice  leaving  the  stomach  is 
called  chyme. 

31.  The  intestine.  —  When 
food  leaves  the  stomach  it  passes 
into  a  coil  of  a  thin  muscular 
tube  called  the  intestine.  The 
intestine  is  about  twenty-five 
feet  in  length.  Its  upper  four  fifths  is  about  an  inch  in 
diameter,  while  the  lowest  one  fifth  is  about  twice  this  size. 
Both  parts  slowly  squeeze  the  food  along,  mixing  it  with 
three  fluids,  which  act  upon  the  food  and  change  it  to  a 
liquid. 

32.  Intestinal  fluids.  —  First.  In  the  mucous  membrane 
of  the  intestine  are  small  tubelike  glands.  They  pour  out 
a  liquid  called  the  "{tetfina!  j^'-Cf  The  intestinal  juice  is 
small  in  quantity,  and  does  not  have  much  effect  upon  the 
food. 

Second.  Behind  the  stomach  is  a  gland  called  the  pan- 
creas or  sweetbread.  Each  day  it  pours  Into  the  intestine 
about  a  quart  of  a  liquid  called  the  pancreatic  juice.  This 
juice  does  most  of  the  work  of  digesting  food.  It  acts 
upon  the  albumin  left  by  the  stomach,  and  changes  it  to 


b  heart. 

c  diaphragm. 


e  liver. 
/  intestine. 


DIGESTION 


liquid  peptone.  It  changes  starch  to  sugar,  but  far  more 
powerfully  than  the  saliva.  It  causes  fat  to  become  broken 
into  fine  particles,  which  will  mix  with  water.  It  also 
changes  some  fat  to  soap. 

Third.  Above  the  stomach  there  is  a  large  red  gland 
^called  the  liver.  Each  day  it  pours  into  the  intestine 
about  a  quart  of  a  yellow  and 
bitter  liquid  called  bile.  Bile 
itself  does  but"  little  of  the 
work  of  digestion,  but  its  pres- 
ence doubles  the  power  of  the 
pancreatic  juice.  Bile  is  a 
waste  substance,  but  on  its 
way  out  of  the  body  it  helps 
in  the  work  of  building  up  the 
body. 

33.  Movements  of  the  intes- 
tine. —  Like    the    mouth    and 
stomach,  the    intestine    mixes 
the  food  with  the  juices,  and 

forces  it  alone:   its   tube.     As  a  ePithelium  <>f  the  surface  of  the 

0  stomach, 

food   goes   farther   and  farther    b  epithelium  lining  the  tubes  of  the 

down,  it    becomes    more    and        glands. 

c  connective  tissue  between  the  tubes. 

more  liquid,  until  at  the  end 

only  such  things  as  very  large  lumps  of  food,  or  husks  and 
peelings,  remain  solid.  The  food  now  looks  like  milk, 
with  undigested  particles  floating  in  it.  It  is  still  as  much 
outside  the  body  as  though  it  were  held  in  the  closed 
mouth.  It  must  pass  through  the  wall  of  the  intestine 
and  enter  the  blood  stream  before  it  can  feed  the  cells. 

34.  How  food  gets  into  the  blood.  —  Many  blood  tubes 
lie  almost  upon  the  surface  of  the  intestine,  while  many 
more  lie  upon  tiny  fingers  called  villi,  which  reach  from 


Gastric  glands  in  the  stomach 

(X200). 


24  APPLIED   PHYSIOLOGY 

the  sides  of  the  intestine  into  the  liquid  food.  Peptone 
and  sugar  easily  soak  into  these  blood  tubes,  and  are  car- 
ried to  the  liver.  There  the  liver  cells  change  the  peptone 
back  to  a  form  of  albumin  much  like  that  which  was  eaten. 
It  is  then  fit  food  for  the  cells,  and  is  sent  to  all  parts  of 
the  body  with  the  blood.  The  liver  cells  also  change  the 
sugar  to  a  kind  of  starch.  This  is  soon  oxidized  in  the 
liver,  and  heat  is  produced  for  the  use  of  the  body. 

Fat  is  soaked  up  by  another  set  of  tubes  called  lacteals. 
The  lacteals  begin  in  the  villi,  and  finally  empty  the  fat 
into  a  blood  tube  in  the  neck.  The  fat  is  then  carried  to 
the  lungs,  where  it  is  oxidized  so  as  to  produce  heat  for 
the  body. 

35.  Action  of  the  bowels.  —  As  the  food  slowly  passes 
down  the  intestine,  its  liquid  parts  soak  into  the  blood 
tubes,  so  that  by  the  time  it  reaches  the  large  intestine 
most  of  its  water  and  all  its  useful  parts  have  been  removed, 
and  only  waste  matter  is  left,  which  is  driven  on  and  out 
of  the  body.      These  waste  matters   should   be  expelled 
regularly  at  least  once  a  day.     If  it  is  done  at  a  certain 
time,  the  intestine  will  form  the  habit  of  always  acting  at 
that  time.     If  the  waste  matters  are  not  given  off,  we  have 
headaches,  and  may  become  sick,  for  they  poison  the  body. 

36.  Use  of  the  liver.  —  If  poisons  are  swallowed,  they 
too  are  taken  up  by  the  blood  tubes,  and  are  carried  to  the 
liver.     The  liver  cells  strive  to  keep  these  poisons  from 
going  farther  along  the  blood  tubes,  and  thus  they  protect 
the  body  against  bad  food.     So  the  liver  has  very  impor- 
tant uses.     When  it  gets  out  of  order,  it  sends  but  little 
bile  to  digest  the  food.     It  lets  poisons  from  the  intestine 
pass  by,  and  does  not  change  the  digested  food  to  a  form 
suited  to  the  cells  of  the  body.     The  result  is  a  kind  of 
sickness  called  biliousness. 


DIGESTION  25 

37.  Digestion  of  water  and  minerals.  —  Water  and  min- 
erals need  no  digestion,  but  are  taken  up  at  once  by 
the  blood  tubes.  Water  is  always  being  poured  into  the 
mouth,  stomach,  and  intestine  by  the  glands,  but  is  soon 
taken  up  again  by  the  blood  tubes.  In  all,  about  twelve 
quarts  of  water  enter  and  leave  these  parts  each  day.  As 
only  two  or  three  quarts  are  swallowed  each  day,  the  same 
water  is  used  over  and  over  again. 

SUMMARY 

1.  Making  food  a  liquid  so  that  it  can  reach  and  feed  the 

cells  of  the  body  is  digestion. 

2.  Cooking  begins  digestion  by  softening  the  food. 

3.  The  mouth  grinds  the  food  and  mixes  it  with   the 

saliva  which  changes  some  starch  to  sugar. 

4.  The  stomach  mixes  the  food  with  the  gastric  juice, 

and  continually  stirs  it  about.      The  gastric  juice 
dissolves  some  of  the  albumin  to  rjeptone. 

5.  In  the  intestine  the  bile  and  par>™-qa,tic  jmc.fr  ^hanpre 

albumin  to  peptone  and  starch  to  sugar,  and  break 
the  fat  into  fine  particles. 

6.  Digested  albumin  and  sugar  soak  into  the  blood  tubes 

and  are  carried  to  the  liver.      Digested  fat  soaks 
into  the  lacteals,   and  is  emptied  into   the   blood 
stream  in  the  neck. 
/.    The  liver  makes  the  ajhiimjrijLpart  °f  tligJlklgd- 

8.  The  liver  changes  the  sugar  back  to  a  form  of  starch 

and  oxidizes  it,  producing  heat. 

9.  The  liver  also  strains  out  poisons  from  the  blood. 

10.  Digested  fat  is  carried  to  the   lungs,   and   is   there 

oxidized. 

11.  Water  and  mineral  substances  enter  the  blood  without 

being  digested. 


CHAPTER    III 


FOODS 

38.  Kinds  of  substances  in  food.  —  A  few  hours  after 
eating,  all  the  food  is  used  by  the  cells  of  the  body,  and 
then  they  ask  for  more  through  the  feelings  of  hunger  and 
thirst.  To  satisfy  these  feelings,  man  uses  many  different 
kinds  of  food,  all  containing  either  water,  albumin,  fat, 
starch,  or  mineral  substances. 


2  eggs. 


£  Ib.  of  bread.  3  pints  of  water. 

Food  required  daily  by  a  healthy 


1 1  pints  of  milk. 


39.  Why  sugar  is  fattening.  —  The  fat  of  the  body  is 
formed  from  albumin.  When  much  sugar  is  eaten,  it  is 
oxidized  in  place  of  the  albumin  and  fat.  These  remain 
and  make  the  body  heavier.  So  we  say  that  sugar  is 
fattening.  But  sugar  gives  only  heat  and  power  to  the 
body.  Albumin  gives  weight,  heat,  and  power,  while 
water  and  minerals  give  weight  only. 

26 


FOODS  27 

40.  Difference  in  foods.  -. —  Water  and  mineral  substances 
are  the  same  everywhere,  except  as  other  things  are  mixed 
with  them.     They  are  found  alike  in  all  foods,  and  so  far 
as  they  are  concerned,  it  makes  little  difference  what  kinds 
of  food  are  eaten.     On  the  other  hand,  there  are  many 
kinds  of  albumin,  fat,  and  starch,  and  it 

is  the  differences  among  these  that  make 
the  difference  in  foods. 

41.  Milk.  —  Milk  contains  all  kinds  of 
food    substances,  for  it  has  water,  min- 
erals,    albumin,    fat,    and    sugar.     More- 

over,  these   substances   are   in   the  best      Milk  as  it  appears 

form  for  the  use  of  the  body.     So  milk  under  the  microscope 
,  .     .     J  ,    .      (x  300).    The   drops 

is  the  most  perfect  food   known,  and  is  are  the  fat. 

the  only  food  which  babies  can  eat. 

42.  Cheese.  —  Milk  is  one  eighth  solid  matter.     Of  the 
solid  matter  the  minerals  form  but  a  small   part,  while 
albumin,  fat,  and  sugar  each  form  about  one  third.     The 
albumin  becomes  hard  or  curdled  when  the  milk  turns 
sour,  and  makes  the  milk  like  soft  jelly.     It  is  also  curdled 
in  the  stomach  in  the  first  part  of  digestion.     When  cur- 
dled outside  the  body  and  freed  from  the  water  of  the 
milk,  it  is  called  cheese.     Cheese  usually  contains  the  fat 
of  milk  also.     It  is  a  valuable  food. 

43.  Cream.  —  When   milk    stands   for   a  while,   its  fat 
rises  to  the  top  and  is  called  cream.      If  the  cream  is 
shaken  in  a  churn,  the  fat  collects  in  a  lump  called  butter. 
Cream  and  butter  are  the  most  valuable  forms  of  fat  in 
food. 

44.  How  to  drink  milk.  —  Some  persons  say  that  milk 
is  harmful  to  them.     It  is  likely  to  be  so  when  a  large 
quantity  of  cold  milk  is  swallowed  after  a  full  meal  is 
eaten.     Think  how  a  young  animal  drinks  milk.     It  takes 


28  APPLIED   PHYSIOLOGY 

it  warm,  upon  an  empty  stomach,  and  swallows  it  very 
slowly.  If  a  person  will  drink  warmed  milk,  in  sips, 
before  he  eats,  it  will  rarely  harm  him.  Children  espe- 
cially will  find  milk  the  best  kind  of  food  for  them. 

45.  Eggs.  —  Eggs  are  about  one  fifth  albumin  and  one 
fifth  fat,  and  the  rest  is  water  with  a  little  mineral  matter. 
They  have  no  starch  or  sugar,  and  so  are  not  a  perfect 
food  for  man.     A  perfect  chicken  can  be  formed  from  an 
egg,  for  the  hen  supplies  the  heat  which,  in  man,  comes 
from  the  sugar. 

Eggs  are  easily  digested,  and  form  one  of  the  most 
valuable  foods  in  whatever  form  they  are  eaten.  When 
boiled  for  at  least  ten  minutes  they  are  easily  chewed  fine, 
and  are  readily  digested.  Soft-boiled  eggs  are  next  in 
value. 

Eggs  which  have  been  kept  for  some  time  are  not 
desirable  for  food,  even  though  they  are  not  spoiled. 
They  should  always  be  fresh. 

46.  Meat.  —  Meat  is  the  muscle  of  animals  and  birds. 
It  is  from  one  tenth  to  one  fifth  albumin,  and  has  less 
than  that  amount  of  fat.      It  has  some  mineral  matter, 
while  the  rest  is  water.     It  has  no  starch  or  sugar,  and  so 
is  not  a  perfect  food.     But  it  is  a  valuable  food,  especially 
for  the  young.     No  child  can  be  harmed  by  eating  meat. 
In  fact,  he  should  have  meat  or  eggs  every  day. 

Meat  which  is  salted  or  dried  or  canned  becomes  hard- 
ened so  that  the  digestive  juices  act  upon  it  less  easily. 
So  for  young  persons  or  persons  with  weak  stomachs  it  is 
not  desirable  for  food.  Of  all  the  different  kinds  of  meat, 
beef  is  the  most  easily  digested,  and  pork  the  least.  Most 
kinds  of  fresh  fowl  and  game  are  easily  digested. 

47.  Fish.  —  Fish,  crabs,  oysters,  and  clams  are  forms 
of  meat.     If  they  are  fresh  and  of  good  quality,  they  can 


FOODS  29 

be  eaten  with  as  much  safety  as  beef  or  pork.  Raw 
oysters  are  especially  valuable  for  sick  people,  for  the 
dark  mass  which  is  often  thought  to  be  their  intestine 
is  really  their  liver  and  helps  digest  them. 

48.  Difference  between  animal  and  vegetable  foods.  — 
All  animal  food  is  more  easily  digested  than  vegetable 
food,  and  should  be  used  by  children  and  sick  persons. 
It  contains  little  or  no  starch,  however,  and  some  vege- 
table food  must  be  eaten  for  the  sake  of  its  starch.     All 
vegetable  food  contains  some  albumin  an'd  a  large  amount 
of  starch  or  sugar  and  little  fat.     It  is  possible  to  live  a 
healthy  life  while  eating  only  vegetable  food,  but  this  is  \ 
by  no  means  the  best  kind  of  food. 

49.  Vegetable  food.  —  Bread  is  about  one  half  starch, 
and  one  fifteenth  albumin,  and  hardly  one  seventieth  fat. 
In  it  the  albumin  is  more  easily  digested  than  in  any 
other  kind  of  vegetable  food,  yet  less  so  than  the  albumin 
of  animal  food.     It  is  not  a  perfect  food,  for  the  starch 
is  in  too  large  amount,  but  with  meat  or  eggs  it  is  a 
perfect  food.     With  milk  it  is  also  a  valuable  food,  espe- 
cially for  the  young.      Cake  is  much  like  bread,  but  it 
contains  more  sugar. 

Potatoes  have  a  large  amount  of  starch  and  very  little 
albumin,  and  no  fat.  They  are  good  food  with  meat,  but 
are  hard  to  digest. 

Beans  are  one  fourth  albumin  and  one  half  starch.  For 
a  strong  person  they  are  a  valuable  food,  but  weak  persons 
find  it  hard  to  digest  them. 

Cereals,  like  corn  meal  and  rice,  are  from  two  thirds  to 
three  fourths  starch,  and  only  one  eighth  to  one  fifteenth 
albumin.  Only  corn  contains  much  fat,  but  all  vegetable 
fat  is  hard  to  digest,  and  is  of  little  value  as  food. 

50.  Fruit.  —  Fruit   contains  some  starch  and  albumin 


3O  APPLIED   PHYSIOLOGY 

and  a  great  deal  of  sugar ;  but  all  fruit  is  hard  to  digest, 
and  little  food  is  obtained.  It  is  sometimes  thought  that 
the  acids  and  flavors  of  fruit  give  some  needed  substances 
to  the  cells  of  the  body,  but  their  main  use  is  their  taste. 
Fruit  is  of  use  mainly  because  it  is  not  digested ;  but,  in 
passing  down  the  intestine,  it  sweeps  along  food  and  waste 
substances,  and  thus  keeps  the  intestine  clean  and  in  good 
condition.  A  great  danger  in  using  fruit  is  that  it  may 
sour  and  decay  in  the  intestine  just  as  it  does  outside  the 
body. 

51.  Sweets.  —  Candy  and  sweet  things  of  all  kinds  con- 
sist mostly  of  sugar,  which  is  digested  and  carried  to  the 
liver.     Thus,  by  eating  too  much  of  them,  one  eats  too 
much  sugar,  and  then  the  liver  is  overworked,  and  a  bilious 
attack  is  produced.     Nuts  contain  a  great  deal  of  albumin 
and  oil,  but  both  are  in  a  form  hard  to  digest. 

Green  vegetables,  such  as  cabbage,  lettuce,  and  beets, 
are  like  fruit,  but  contain  even  less  food  matters.  They 
are  of  value  mainly  for  their  taste. 

52.  Spices.  —  Spices,  such  as  mustard  and  cloves,  burn 
the  stomach  just  as  they  burn  the  mouth.     They  have  no 
value  as  food,  while  by  covering  the  taste  of  bad  food  they 
may  be  harmful.     Still  a  little  may  improve  the  taste  of 
food  and  so  assist  digestion. 

53.  Salt.  —  All  the  foods  named  have  more  than  enough 
mineral  substances,  excepting  salt,  to  supply  the  needs  of 
the  body.     Salt  is  a  great  aid  in  the  digestion  of  food.     It 
also  gives  an  agreeable  taste  to  food.      Food  which  has 
no  taste  can  hardly  be  eaten,  and  after  it  is  eaten  it  is  as 
disagreeable  to  the  stomach  as  it  is  to  the  mouth.     Salt 
gives  food  an  agreeable  flavor.     The  saliva  flows  so  that 
the  mouth  waters.     In  the  stomach  the  gastric  juice  flows 
in  the  same  way,  and  so  the  meal  'is  easily  and  quickly 


FOODS  31 

digested.     Fruit,  nuts,  and  similar  foods  act  upon  the  taste 
in  the  same  way  as  salt. 

54.  Bad  food.  —  Food  which  smells  or  tastes  musty  or 
decayed  is  always  unfit  for  food  and  may  be  poisonous. 
Spoiled  milk  or  cream  is  the  worst  of  all.    Young  children 
and  babies  should  never  drink  milk  which  is  the  least 
sour.     Moldy  bread  or  meat  may  cause  sickness  of  the 
stomach  and  great  pains  in  the  lower  part  of  the  body. 
The  food  of  diseased  animals  is  as  bad  as  spoiled  food. 
Canned  food  should  not  be  opened  until  it  is  to  be  eaten, 
for  it  soon  spoils  when  exposed  to  the  air.  I 

Unripe  fruit  cannot  be  digested  at  all  unless  it  is  cooked. 
Green  apples  or  cherries  are  not  fit  for  any  one.  In  them 
the  starch  and  sugar  are  like  the  starch  in  grass.  But  by 
thorough  cooking  they  may  sometimes  be  made  harmless. 

55.  Diseased  food.  —  Food  may  contain  disease  germs. 
Consumption  is  often  caught  in  this  way.     Meat  is  the 
most  often  diseased ;    and  of  meat,  pork  the  most  often 
contains  disease  germs.     Cooking  destroys  the  germs.    So 
we  should  never  eat  raw  meat. 

56.  Choice  of  food.  —  The  different  kinds  of  meal  and 
flour  are  almost  the  same  in  price.     Meats,  fish,  and  vege- 
tables of  the  same  food  value  differ  greatly  in  their  cost. 
The  variety  of  foods,  or  their  good  appearance,  or  their  un- 
usually fine  taste  makes  them  high-priced.    What  is  called 
the  best  food  may  look  and  taste  better,  but  is  often  no 
more  nourishing  than  cheaper  food.     The  cheaper  meats 
and  fish  furnish  good  food  at  half  the  cost  of  the  best 
kinds.     If  they  are  well  cooked,  they  will  taste  as  good  as 
the  best.    Plain  flour  and  meal  are  cheap,  but  prepared  and 
ready  mixed  kinds  cost  far  more  and  are  no  better  for  food. 

57.  Water.  —  Water  is  also  a  food,  but  we  call  it  a  drink. 
Water  itself  is  everywhere  the  same,  but  different  sub- 


32  APPLIED    PHYSIOLOGY 

stances  dissolved  in  it  make  it  good  or  bad  for  use.  Really 
pure  water  has  a  flat  taste,  and  is  unfit  for  drinking.  Air 
in  the  water  gives  it  a  pleasant  taste.  Water  often  dis- 
solves lime  from  the  soil  so  that  it  does  not  easily  form  a 
lather  with  soap.  We  call  such  water  hard.  Rain  water 
is  softy  for  it  has  no  lime. 


How  impurities  may  get  into  a  well. 

58.  Impure  water.  —  Water  dissolves  many  substances 
over  which  it  runs,  but  only  a  few  of  these  are  harmful. 
When  it  stands  in  lead  pipes  for  some  hours,  it  dissolves  a 
little  poisonous  lead.  If  the  water  that  has  stood  in  the 
pipes  is  thrown  away,  the  running  water  will  be  safe  for  use. 

Almost  the  only  other  dangerous    substance  found   in 


FOODS  33 

water  is  decaying  matter.  Decaying  slops  from  the  house 
or  barnyard  are  very  poisonous.  They  sometimes  soak 
into  the  well  and  poison  the  family.  Disease  germs  can- 
not grow  in  pure  water,  but  they  easily  grow  in  water 
containing  decayed  substances.  Sometimes  the  germs  of 
typhoid  fever  get  into  the  water  of  a  well  and  grow,  pro- 
ducing the  disease  in  those  who  drink  the  water.  Water 
may  be  impure  even  if  it  tastes  good  and  looks  clear  and 
sparkling.  The  surest  way  to  keep  the  water  pure  is  to 
locate  the  well  so  that  no  slops  or  barnyard  drainage  can 
reach  it. 

59.  How  to   purify  water.  —  If  impure  water  must   be 
used,  the  disease  germs  may  be  destroyed  by  boiling  it  for 
ten  minutes.     This  also  drives  out  the  air  and  makes  the 
water  taste  flat,  but  if  it  stands  a  few  hours,  it  takes  up 
air  and   becomes  fit  for  use.     Water   can  be  somewhat 
purified  by  passing  it  through  sand  or  powdered  charcoal 
or  some  other  powdered  substance.     An  arrangement  for 
this  purpose  is  a  filter.     A  filter  removes  mud  and  coarse 
particles,  but  it  does  not  take  out  all  the  disease  germs. 

60.  Amount  of  water  needed.  —  A  grown  person  needs 
about  three  quarts  of  water  daily.     He  will  take  half  of 
this  with  his  solid  food,  leaving  about  a  quart  and  a  half 
to  be  drunk  extra.     We  should  drink  about  this  amount  of 
water  daily.     The  time  of  drinking  is  not  of  great  impor- 
tance.    Some  should  be  taken  at  meal  times,  and,  if  the 
meal  is  eaten  slowly,  it  can  do  no  harm.     All  drinks,  of 
course,  contain  water  which  should  be  counted  as  so  much 
ordinary  water. 

61.  Tea  and  coffee.  —  Tea  and  coffee  are  not  food,  but 
they  act  upon  the  mind  so  that  the  body  does  not  feel  tired 
when  hard  work  is  done.     By  using  a  large  amount  of  tea 
and  coffee  it  would  seem  that  more  work  can  be  done,  yet 

ov.  PHYSIOL.  (INTER.)  —  3 


34  APPLIED   PHYSIOLOGY 

they  do  not  add  to  the  strength  of  the  body,  but  only 
benumb  its  tired  feelings.  A  substance  which  causes  the 
body  to  do  more  work  without  giving  extra  strength  is 
called  a  stimulant.  The  old  Romans  called  an  ox  whip  a 
stimulus.  So  a  stimulant  is  anything  which  acts  like  a 
whip. 

62.  How  much  food  ?  —  In  all,  about  one  fourth  of  a 
pound  of  albumin,  and  a  little  more  than  a  quarter  of 
a  pound  of  starch,  and  a  little  less  than  a  quarter  of  a 
pound  of  fat  should  be  eaten  each  day.  What  food 
shall  we  select  to  furnish  these  substances  ?  Men  live 
upon  every  kind  of  food,  but  some  foods  are  better  than 
others.  This  bill  of  fare  for  the  day  will  give  the  right 
quantity  of  food : 

i  Ib.  of  meat,  or  eggs,  or  fish ;  2  oz.  of  butter ; 

\  Ib.  of  bread;  3  pints  of  water;       i^  pints  of  milk. 

SUI&MARY 

1.  All  animal  food  contains  a  good  quantity  of  albumin 

and  fat,  and  but  little  starch  or  sugar. 

2.  Vegetable  foods  contain  albumin,  but  it  is  much  harder 

to  digest  than  the  albumin  of  animal  food. 

3.  Vegetable  food  contains  some  oil,  but  this  is  scarcely 

digested  at  all. 

4.  Vegetable  food  contains  a  very  large  quantity  either  of 

starch  or  of  sugar. 

5.  The  best  bill  of  fare  contains  animal  food  to  supply 

the  albumin  and  fat,  and  vegetable  food  to  supply 
the  sugar  or  starch. 

6.  Salt  is  the  only  mineral  substance  which  needs  to  be 

added  to  food. 

7.  Almost  any  kind  of  water  can  be  made  safe  for  drink- 

ing by  boiling  it  for  ten  minutes. 


CHAPTER   IV 
INTEMPERANCE  AND  POISONS 

63.  Why  men  are  intemperate.  —  If  a  man  should  eat  as 
nature  intended,  he  would  always  be  strong  and  healthy. 
In  caring  for  animals  we  feed  them  only  one  or  two  kinds 
of  food,  and  are  very  careful  not  to  overfeed  them.      If 
they  have  too  much  food,  or  too  many  different  kinds  of 
food,  they  become  sick.     We  sometimes  say  that  a  per- 
son has  the  stomach  of  an  animal,  for  nothing  seems  to 
hurt  him.     But  if  the  stomachs  of  animals  were  treated  as 
the  stomachs  of  men  are  commonly  treated,  animals  would 
become  sick  sooner  than  men. 

Improper  eating  and  improper  drinking  produce  more 
ill  health  than  all  other  causes  put  together.  Many 
parents  feed  their  children  with  sweets  and  candy.  Some 
give  them  tea  and  coffee,  and  some  give  them  beer  or 
wine.  These  things  create  a  craving  which  increases  its 
demands  if  it  is  gratified,  and  thus  paves  the  way  for  the 
desire  for  strong  drink. 

Man  is  surrounded  by  an  abundance  of  all  kinds  of  good 
food,  and  is  given  a  plenty  of  time  for  eating  it.  Yet,  in 
spite  of  his  knowledge  and  opportunities,  he  often  makes 
himself  sick  by  his  eating  and  drinking.  He  is  led  to  do 
this  by  making  a  wrong  use  of  the  very  feelings  which 
should  teach  him  how  to  eat  properly. 

64.  Hunger  and  thirst.  —  Nature  has  given  man  signs 
so  that  his  mind  may  know  when  and  what  kind  of  food 

35 


36  APPLIED  PHYSIOLOGY 

to  eat.  The  sense  of  taste  is  a  sure  guide  as  to  the  kind 
of  food  that  is  needed.  Man  never  tires  of  bread  and 
meat,  but  he  does  tire  of  spices  and  sweet  things,  which 
are  not  proper  foods.  Hunger,  or  the  appetite,  is  a  sign 
when  food  is  needed.  Grown  people  get  hungry  about 
every  six  hours,  and  children  more  often.  When  enough 
food  has  been  eaten  there  is  a  feeling  that  the  hunger  is 
satisfied.  If  we  should  always  heed  these  two  signs,  it 
would  be  much  better  for  us. 

65.  False  appetites.  —  But  we  can  teach  the  taste  and 
appetite  so  that  they  are  no  longer  sure  guides.     After  a 
full  dinner  has  been  eaten,  and  when  the  appetite  has  been 
satisfied  with  plain  food,  a  dessert  made  of  sweets,  spices 
and  jellies  is  brought  in.     This  at  once  makes  a  new  appe- 
tite, and  man  satisfies  it  for  the  sake  of  his  pleasure.     So 
he  does  two  wrong  things  to  his  body.     First,  he  puts  too 
much  food  into  his  stomach ;    second,  he  eats  too  much 
sugar.     The  sugar  overworks   the  liver,  and  he  is  very 
liable  to  have  a  bilious  attack.      We  need  a  little   more 
sugar  than  fat,  but  we  often  eat  many  times  as  much.     A 
natural  appetite  is  satisfied  with  three  meals  a  day,  but  the 
false  appetite  leads  us  to  eat  cake,  candy,  and  fruit  at  all 
times.     We  seldom  want  to  eat  bread  or  meat  between 
meals.     This  shows  that  the  cells  of  the  body  are  not  call- 
ing for  food.     By  eating  at  all  hours  we  keep  the  stomach 
at  work  without  rest,  and  it  soon  tires  itself  out. 

66.  Too  fast  eating.  —  When  we  eat  too  fast,  the  food 
cannot  be  chewed  fine,  but  is  swallowed  in  lumps.     Then 
the  stomach  must  do  the  work  which  the  mouth  should  do. 
Besides,  it  does  not  have  time  to  give  notice  that  its  wants 
are  filled,  and  so  we  eat  too  much.     When  we  need  to 
wash  food  down  with  water,  we  are  surely  eating  too  fast, 
but  drinking  at  meals  to  satisfy  a  natural  thirst  is  proper. 


INTEMPERANCE  AND    POISONS 


37 


Our  appetite  sometimes  leads  us  to  drink  very  hot  or 
very  cold  water  or  tea.  Although  we  cannot  feel  either 
in  the  stomach,  yet  both  disturb  digestion. 


One  form  of  intemperance. 

67.  Intemperance.  —  Man  is  almost  the  only  living  being 
that  eats  all  kinds  of  food  for  the  mere  pleasure  of  eating. 
Animals  follow  their  natural  appetites,  and  their  stomachs 
are  healthy.  Man  eats  to  satisfy  new  appetites,  and  harms 
his  stomach  so  that  it  cannot  digest  even  plain  food.  We 
should  be  far  better  off  if  we  never  touched  sweetmeats, 
pie,  and  cake,  but  lived  only  upon  bread  and  meat  and 
other  plain  foods. 

Satisfying  an  appetite  which  does  not  indicate  a  need  of 


38  APPLIED   PHYSIOLOGY 

the  body  is  intemperance.  Almost  everybody  is  intem- 
perate in  eating  from  the  time  he  can  walk,  to  old  age. 
Intemperance  in  eating  is  very  liable  to  lead  to  intemper- 
ance in  drinking  later  in  life. 

Eating  and  drinking  anything  for  mere  pleasure  is  in- 
temperance and  harms  the  body.  We  may  not  see  the 
harm  of  eating  a  single  apple  in  the  middle  of  the  fore- 
noon when  we  are  not  hungry ;  and  yet  this  is  an  act  of 
intemperance,  and,  if  repeated,  tends  to  overwork  the 
stomach  and  to  produce  dyspepsia,  and  possibly  a  fever. 
Eating  some  other  things,  such  as  green  apples,  nearly 
always  produces  sickness,  and  we  at  once  see  that  it  is 
a  form  of  intemperance.  But  eating  the  first  apple  was 
intemperance  just  as  really  as  eating  the  green  one. 

A  little  pie  or  cake  may  be  used  in  place  of  plain  food, 
but  every  one  knows  that  eating  much  of  it  is  intemper- 
ance and  produces  sickness. 

In  some  cases  a  great  deal  of  intemperance  does  not 
seem  to  do  harm  at  once,  and  so  men  will  risk  being  sick 
for  the  sake  of  a  moment's  pleasure.  They  do  not  count 
the  cost  when  they  are  feeding  an  appetite. 

68.  Appetite  for  strong  drink.  —  Using  drinks  which 
contain  alcohol  is  the  worst  form  of  intemperance.  It  is 
such  a  bad  form  that,  when  we  speak  of  intemperance  we 
usually  mean  the  use  of  strong  drink. 

We  can  eat  pie  or  cake  or  candy  without  being  intem- 
perate ;  but  any  use  of  strong  drink  is  intemperance,  for  it 
is  not  needed  at  all  by  the  body,  but  is  used  only  for 
pleasure.  It  does  such  harm  that  no  one  can  drink  much 
without  plainly  showing  its  effects. 

When  we  have  been  intemperate  in  eating  pie  or  cake 
we  feel  sick  and  could  not  eat  more  if  we  would.  When  a 
person  is  harmed  by  strong  drink  the  drink  often  makes 


INTEMPERANCE  AND   POISONS  39 

him  feel  well  while  he  is  slowly  killing  himself.  This 
power  of  strong  drink  to  deceive  a  person  into  using  it 
while  it  is  slowly  harming  him  makes  it  the  worst  form  of 
intemperance.  It  affects  every  part  of  the  body.  These 
effects  will  be  described  fully  as  we  study  the  different 
parts  of  the  body. 

69.  Tobacco  intemperance.  —  Next  to  using  strong  drink, 
the  use  of  tobacco  is  the  most  harmful  form  of  intemper- 
ance.    It  does  not  always  do  so  much  harm  as  strong  drink, 
for  it  usually  acts  so  slowly  that  we  do  not  notice  its  effects. 
Like  strong  drink,  it  makes  a  person  feel  well  while  it 
slowly  poisons  him.     It  often  does  great  harm  to  different 
parts  of  the  body.     These  effects  will  be  described  as  we 
study  each  part. 

70.  Sickness.  —  When  each  cell  of  our  body  does  its 
work  perfectly,  and  when  all  the  cells  work  together,  we 
are  well  and  healthy.     When  one  set  of  cells  is  out  of 
order,  it  affects  all  the  others,  arid  we  are  sick.     Thus,  if 
the  cells  of  the  stomach  fail  to  digest  food,  all  the  cells 
lack  food,  and  so  the  stomach  makes  the  whole  body  feel 
sick.    The  doctor  then  comes  to  see  what  was  out  of  order 
first,  and  tries  to  correct  its  action  so  that  we  may  be  well 
again. 

71.  Drugs.  —  When  a  person  is  sick,  the  doctor  often 
gives  him  substances  which  are  called  drugs.     They  are 
not  food,  and  even  if  they  were,  they  are  in  too  small 
amounts  to  furnish  much  nourishment.     In  the  stomach 
and  intestine  they  are  taken  up  with  the  food,  and  are 
carried  by  the  blood  to  the  cells  of  the  body.     There  they 
cause  the  cells  to  act  in  a  more  natural  manner.     When 
the  cells  finally  act  as  usual,  we  are  well  again.     For  in- 
stance, in  a  bilious  attack,  the  doctor  gives  a  pill  or  powder, 
which  is  taken  up  by  the  blood  and  carried  to  the  liver. 


40  APPLIED   PHYSIOLOGY 

There  it  causes  the  liver  cells  to  act  more  strongly  and  to 
produce  more  bile.  In  a  short  time,  the  liver  is  acting  right 
again,  and  we  are  well.  In  the  same  way,  other  drugs  act 
upon  other  parts  of  the  body  and  make  them  act  rightly 
when  they  are  out  of  order. 

72.  Poisons.  —  A  little  of  a  drug  causes  the  cells  of  the 
body  to  act  in  a  more  natural  way.     Too  much  of  a  drug 
either  causes  them  to  overwork,  or  else  stops  their  action, 
in  either  case  producing  sickness.    Substances  which  inter- 
fere with  the  work  of  the  the  cells  are  poisons.     So  all 
drugs   and   narcotics  are  poisons  if   taken   in   too   great 
amounts.     For  this  reason,  we  should  never  use  them  un- 
less we  are  guided  by  some  one  who  understands  their  use. 

73.  Signs  of  poisoning.  —  When  a  person  is  poisoned, 
he  suddenly  becomes  very  sick  and  weak.     There  is  no 
sickness  that  will  come  on  so  suddenly  as  that  caused  by 
poisoning.    The  sufferer's  mind  will  probably  be  affected, 
and  he  will  be  much  alarmed  for  himself. 

74.  How  to  help  a  poisoned  person.  —  When  a  person  is 
poisoned,  the  first  thing  to  do  is  to  get  rid  of  the  poison 
as  soon  as  you  can.     This  you  will  do  by  making  the  per- 
son vomit.     You  can  always  do  this  at  once  by  running 
your  finger  down  his  throat  as  far  as  possible.     Do  not 
get  frightened,  but  at  once  either  ask  the  person  to  do 
it  himself  or  to  let  you  do  it. 

You  will  also  help  vomiting  by  having  the  person  drink 
as  much  water  as  possible.  This  will  also  wash  out  his 
stomach  and  get  rid  of  more  of  the  poison. 

You  will  also  aid  vomiting  by  giving  a  tablespoonful 
of  mustard  mixed  in  water.  The  point  is  to  get  the  per- 
son to  vomit  as  soon  as  possible.  By  remembering  this, 
you  may  be  able  to  save  a  life. 

A  poisoned  person  will  feel  very  weak  after  he  has 


INTEMPERANCE  AND   POISONS  41 

vomited.  So  you  must  give  him  a  stimulant.  Some  strong 
coffee  will  be  the  best  of  all.  You  will  do  him  no  harm 
by  giving  it. 

Finally,  keep  the  person  quiet,  for  in  his  weakness  he 
cannot  stand  much  exertion  in  moving  about. 

75.  Spoiled  food  or  poisonous  food,  such  as  some  varie- 
ties of  mushrooms,  causes  great  pain  in  the  lower  part  of 
the  body,  and  great  weakness.    When  this  comes  on,  vomit- 
ing should  be  induced  at  once.     Often  the  stomach  will 
vomit  the  food  of  its  own  accord,  and  so  nature  cures  the 
poisoning.     When  a  person  vomits,  it  usually  means  that 
some  poison  is  upon  the  stomach. 

76.  Opium  poisoning.  —  The  most  common  form  of  poi- 
soning is  that  by  opium.     Opium  is  the  dried  juice  of  the 
poppy  plant.     It  is  used  to  produce  sleep  and  to  relieve 
pain,  and  is  a  strong  poison.     A  piece  as  large  as  a  grain 
of  corn  could  put  a  man  into  a  deep  sleep,  and  three  or 
four  such  pieces  might  kill  him. 

People  often  keep  different  kinds  of  opium  in  the  house. 
Laudanum  is  opium  dissolved  in  nine  times  its  weight  of 
alcohol.  Paregoric  is  a  weaker  form  of  opium  and  alcohol. 
Most  soothing  syrups  which  are  used  to  quiet  children,  act 
by  means  of  their  opium.  They  can  easily  poison  a  baby. 
Morphine  is  a  powder  made  from  opium,  and  is  ten  times 
as  strong  as  opium  itself. 

You  can  tell  opium  poisoning  by  the  deep  sleep  which  it 
produces.  A  poisoned  person  should  be  made  to  vomit, 
and  afterward  he  should  drink  some  strong  coffee.  You 
should  also  keep  him  awake  by  making  him  walk  or  even 
by  striking  him  with  a  whip ;  but  do  not  bruise  his  skin. 

77.  Carbolic  acid  poisoning.  —  Carbolic  acid  is  often  kept 
in  houses  for  use  as  a  wash  during  sickness.     If  it  is  swal- 
lowed it  will  burn  the  throat  and  stomach,  leaving  a  white 


42  APPLIED   PHYSIOLOGY 

scar.  The  person  will  feel  very  sick  and  may  faint  away 
and  become  insensible.  You  should  give  him  milk  or  raw 
eggs.  Then  give  Epsom  salts,  which  will  tend  to  stop  the 
action  of  the  poison.  Carbolic  acid,  when  used  as  a  strong 
wash,  may  injure  the  skin,  and  cause  sickness  as  if  it  had 
been  swallowed.  Treat  the  person  as  if  he  had  swallowed 
the  poison. 

78.  Arsenic.  —  Paris   green,  London  purple,  and   most 
other  rat  and  insect  poisons  are  forms  of  arsenic.     When 
swallowed  they  produce  vomiting  and  great  pains  in  the 
stomach.     A  very  little  of  the  poison  will  cause  death. 
Give  the  poisoned  person  milk  and  raw  eggs. 

79.  Insect  stings.  —  Bees,  hornets,  spiders,  mosquitoes, 
and  other  insects  sometimes  inject  a  little  poison  beneath 
the  skin  when  they  bite  or  sting.     This  produces  a  swelling 
and  great  pain  as  though  something  were  burning  the  skin. 
If  a  number  of  stings  are  made  there  may  be  enough  poison 
to  make  a  person  very  sick. 

The  pain  of  bites  and  stings  can  be  relieved  by  applying 
a  lump  of  cold  mud  at  once.  Some  carbolic  acid  water, 
lime  water,  ammonia,  or  camphor  will  also  help. 

80.  Snake  bites.  —  In  the  United  States  there  are  but 
few  kinds  of  snakes  that  bite,  and  still  fewer  whose  bites 
are  poisonous.     A  snake  bite  is  like  that  of  a  very  large 
and  poisonous  insect.     The  bitten  part  swells  and  becomes 
very  painful,  and  the  person  feels  weak  all  over. 

You  should  tie  a  handkerchief  above  the  bite  as  soon  as 
possible,  so  as  to  keep  the  poison  from  going  through  the 
whole  body.  Then  suck  the  bite  so  as  to  take  out  the 
poison,  being  careful  to  spit  out  the  blood  and  poison. 
You  should  cut  open  the  bitten  part  so  as  to  let  the  blood 
flow  and  wash  away  the  poison.  You  should  also  give 
strong  coffee  or  other  stimulant. 


INTEMPERANCE  AND   POISONS  43 

SUMMARY 

1.  The  taste  and  the  appetite  are  two  sure  signs  of  when 

and  how  much  food  to  eat. 

2.  Man  spoils  these  signs  by  eating  sweet  and  spicy  foods 

at  all  hours  for  the  sake  of  the  pleasure  of  eating, 
and  by  eating  too  fast. 

3.  Eating  for  the  pleasure  of  eating  when  the  body  does 

not  need  food  is  as  real  intemperance  as  taking 
strong  drink. 

4.  Sickness  is  due  to  the  imperfect  or  stopped  action  of 

some  of  the  cells  of  the  body.  Drugs  are  then  given 
to  cause  the  cells  to  act  rightly  again. 

5.  Too  much  of  any  drug  hinders  the  action  of  the  cells, 

and  so  is  a  poison. 

6.  When  a  person  is  poisoned,  cause  him  to  vomit  by  put- 

ting the  finger  down  the  throat,  or  by  giving  him 
large  drinks  of  water,  or  by  giving  him  mustard  and 
water. 

7.  Also  give  a  poisoned  person  strong  coffee. 


CHAPTER   V 
TOBACCO 

81.  Narcotics.  —  Besides  eating  his  natural  food,  man 
often  forms  a  habit  of  eating  things  which  harm  him,  and 
yet  he  uses  them  because  he  learns  to  enjoy  their  taste  or 
the  feelings  which  they  produce.     Most  of  these  things 
belong  to  a  class  called  narcotics ;  they  benumb  pain  and 
weaken  both  the  brain  and  the  body.     At  first,  both  these 
substances  themselves  and  also  the  feelings  which  they 
produce  are  unpleasant.     Men  learn  to  like  their  benumb- 
ing effects,  and  soon  get  into  the  habit  of  their  use  because 
they  take  away  pain  and  calm  a  person  when  he  is  nervous 
or  worried.     The  most  commonly  used  narcotic  is  tobacco. 

82.  Tobacco.  —  Tobacco  is  the  leaf  of  a  tall  plant.     It 
requires  a  richer  soil  and  more  care  than  any  other  crop. 
Soil  which  raises  tobacco   is  kept  from  raising  a  great 
quantity  of  real  food.     A  few  crops  of  tobacco  take  so 
much  richness  from  the  soil  that  only  small  crops  of  any- 
thing else  will  grow  afterwards. 

The  leaves  of  tobacco  contain  a  narcotic  poison  called 
nicotine.  Nicotine  gives  the  tobacco  most  of  its  smell  and 
taste,  and  if  it  is  taken  out,  the  tobacco  is  spoiled.  It  is 
easily  turned  into  a  vapor,  and  is  found  in  the  smoke  when 
tobacco  is  burned.  It  is  so  poisonous  that  the  smoke  of 
two  or  three  pipefuls  of  tobacco  contains  enough  to  kill  a 
man  if  it  should  stay  in  his  body.  A  single  drop  of  it  can 
kill  a  strong  person.  Tobacco  is  sometimes  made  into  a 

44 


TOBACCO  45 

poultice  and  put  upon  a  sore.  The  nicotine  from  the  poul- 
tice has  been  known  to  poison  the  body,  .and  even  to  pro- 
duce death.  The  nicotine  of  a  few  puffs  of  smoke  makes 
a  person  very  weak  and  sick  when  he  begins  to  smoke. 
This  shows  how  poisonous  it  is.  After  a  person  has 
smoked  a  few  times  he  becomes  used  to  the  poison  so  that 
he  can  smoke  or  chew  a  great  deal  without  becoming  sick, 
but  a  larger  amount  than  usual  sickens  even  an  old  smoker. 

83.  Why  tobacco  is  used.  —  Persons  make  many  excuses 
for   using   tobacco.      One    says    it   is    company  for   him. 
Another  says  it  makes  his  head  clear  so  that  he  can  think 
better.     Some  smoke  because  others  do,  and  boys  smoke 
because  they  think  it  makes  them  look  like  grown  men. 
Some  say  that  they  smoke  to  help  digest  the  food,  and 
some  that  they  use  tobacco  so  that  their  stomachs  will  not 
need  so  much  food.     Some  smoke  to  cure  a  cold  in  the 
head.     Some  boys  learn  to  chew  by  putting  tobacco  in  a 
decayed  tooth,  thinking  it  will  stop  toothache.     It  is  easy 
to  find  an  excuse  for  using  tobacco,  but  where  so  many 
excuses  are  given,  none  are  good. 

84.  Why  tobacco  should  not  be  used.  —  There  are  many 
reasons  why  a  person  should  not  use  tobaeco  in  any  form. 
It  always  leaves  an  unpleasant  odor  about  the  clothes  and 
room,  and  upon  the  breath.     A  person  who  cares  for  the 
feelings  of  others  will  not  make  himself  disagreeable  with 
the  smoke  of  tobacco. 

Chewing  and  smoking  make  more  saliva  flow  than  the 
mouth  can  take  care  of.  The  spitting  which  this  causes 
ought  to  keep  any  one  from  using  tobacco.  Tobacco  does 
not  help  digestion,  but  those  who  use  it  are  very  apt  to 
have  a  coated  tongue  and  headache,  showing  that  their 
food  is  not  digested  as  it  should  be.  Many  also  have  a 
sore  throat  and  a  cough  and  a  husky  voice  as  the  direct 


46  APPLIED   PHYSIOLOGY 

result  of  using  tobacco.  The  worst  effects  are  that  it 
sometimes  causes  weakness  of  the  heart  and  poor  sight,  or 
even  blindness.  These  effects  will  be  studied  later. 

All  these  bad  effects  can  be  produced  in  those  who 
breathe  the  smoke  in  a  room.  Babies  can  easily  be  made 
sick  by  tobacco  smoke  in  a  room  with  them.  The  young 
are  far  more  easily  poisoned  by  tobacco  than  older  per- 
sons. In  the  young  the  weakness  caused  by  tobacco  is 
often  so  great  as  to  hinder  the  growth  of  the  body.  .  Boys 
who  wish  to  grow  to  be  large  men  had  better  not  use 
tobacco.  In  a  crowd  of  boys  it  is  often  possible  to  pick 
out  those  who  smoke  by  their  smaller  size,  the  thinness  of 
their  flesh,  and  their  pale,  pasty  complexion. 

85.  Smoking.  —  Tobacco   is   used    either    by   smoking, 
chewing,  or  as  snuff.     All  tobacco  smoke  is  poisonous,  but 
the  stronger  the  tobacco,  the  more  poisonous  it  is.     The 
burning  also  makes  poisonous  gases,  one  of  which  is  a 
dangerous  gas  like  that  used   in  lighting  houses.      The 
poisons  stay  in  the  stem  of  a  pipe  which  has  been  smoked 
for  some  time  until  so  much  collects  that  it  makes  even  an 
old  smoker  sick.     The  smoke  of  a  pipe  contains  more 
poisons  than  the  smoke  of  a  cigar,  for  the  cigar  is  more 
completely  burned  up. 

86.  Cigarettes.  —  Cigarettes  are  made  from  mild  tobacco 
and  contain  less  nicotine,  yet  the  danger  from  using  them 
is  still  greater,  for  the  smoke  is  easily  drawn  deeply  into 
the  mouth  and  often  into  the  lungs,  and  so  more  of  the 
poison  is  apt  to  reach  the  cells  of  the  body. 

87.  Chewing.  —  Chewing  tobacco  is  a  dirty  habit  which 
has  no  excuse  beyond  the  pleasure  men  learn  to  take  in  it. 
No  man  who  prides  himself  upon  the  good  looks  of  his 
teeth  and  lips  will  chew  tobacco.     It  is  the  most  poisonous 
of  all  the  forms  in  which  tobacco  can  be  used. 


TOBACCO  47 

88.  Snuff.  —  Taking    snuff    is    going    out    of    fashion. 
Snuff  is  used  to   produce  a  sneeze.     It  may  be  fun  to 
make  oneself  sneeze,  but  snuff  is  poisonous  and  is  a  bad 
thing  to  use  for  this  purpose.     A  sneeze  is  really  an  at- 
tempt to  drive  out  something  which  is  hurting  the  nose. 
Surely  it  does  not  pay  to  hurt  the  nose  for  a  sneeze. 

We  all  know  of  men,  and  even  women,  who  chew  and 
smoke  every  day  and  yet  live  long  and  healthy  lives. 
If  tobacco  evidently  harmed  every  one  who  uses  it,  the 
law  would  have  stopped  its  use  long  ago.  But  because 
its  hurtfulness  shows  itself  only  slowly  and  because  the 
body  can  become  somewhat  used  to  it,  men  say  it  is  harm- 
less, and  some  even  say  it  is  good  for  the  body.  The  truth 
is  that  tobacco  will  surely  do  a  great  harm  to  at  least  one 
quarter  of  those  who  use  it,  and  may  harm  the  others  at 
any  time. 

89.  Opium.  —  Opium   is    another   narcotic   which    men 
learn  to  use.     It  is  the  dried  juice  of  the  poppy  plant.     It 
stops  pain,  produces  sleep,  and  gives  nervous  people  a 
calm  and  contented  feeling.     Many  different  substances 
in  the  opium   can   do  this,  but  a  white  substance  called 
morphine  is  the  main  one.     In  large  doses,  opium  or  mor- 
phine causes  deep  sleep  and  great  weakness  of  the  body 
until  death  occurs.     In  small  doses  it  hinders  the  work  of 
the  stomach  and  intestine,  so  that  food  is  not  digested  as 
it  should  be.     So  the  body  loses  weight   and    strength. 
The  body  may  get  used  to  the  drug  so  that  more  and  more 
is   needed   to   quiet  the   nerves.     It   always  weakens  the 
body  and  causes  death  in  a  few  months  or  years.     The 
opium  habit  is  one  of  the  hardest  to  break.     Some  use 
opium  by  smoking  it  like  tobacco. 

90.  Chloral.  —  Chloral  is  a  solid  with  a  sharp,  peppery 
taste.     It  is  used  much  like  opium.     It  calms  nervousness 


48  APPLIED   PHYSIOLOGY 

and  causes  sleep,  but  it  poisons  the  body  and  produces 
death  even  more  quickly  than  opium. 

91.  Narcotic  poisoning.  —  Poisoning  by  opium  and  such 
drugs  produces  sleep.  So  the  poisoned  person  must  be 
kept  awake.  One  must  shake  or  pinch  him,  or,  in  fact,  do 
almost  anything  to  arouse  him,  for  if  he  gets  sound  asleep 
he  is  liable  to  die. 

SUMMARY 

1.  Men  use  narcotics  to  benumb  pain  and  to  dull  the  brain 

so  that  it  does  not  worry. 

2.  Tobacco  is  a  narcotic  which  depends  upon  a  poison 

called  nicotine  for  its  effects. 

3.  Tobacco  is  smoked,  chewed,  and  snuffed  up  the  nose. 

In  all  three  ways,  nicotine  enters  the  body. 

4.  Tobacco  not  only  harms  those  who  use  it,  but  its  use  is 

unpleasant  to  those  who  do  not  use  it. 

5.  Opium  is  a  narcotic  used  to  produce  sleep  and  to  quiet 

pain.     Its  use  always  does  great  harm,  and  if  con- 
tinued produces  death. 

6.  Chloral  is  used  like  opium,  and  is  even  more  deadly. 

7.  A  person  must  be  kept  awake  when  he  is  poisoned  by 

a  narcotic. 


CHAPTER   VI 


ALCOHOL 

92.  Yeast.  —  A  narcotic  which  man  often  takes  into  his 
body  is  alcohol.     When  a  little  sugar  in  water  stands  a 
while,  bubbles  of  carbonic  acid  gas  rise  up  through  the 
water,  and  the  liquid  turns  sour.     If  one  puts  more  sugar 
in   the   water,   the   bubbles   will   rise, 

but  the  liquid  has  a  strong  odor  and 
a  sharp  taste,  for  some  of  the  sugar 
has  turned  to  alcohol.  We  say  that 
the  sugar  ferments.  When  there  is  a 
great  deal  of  sugar  in  the  water,  it 
does  not  ferment  at  all.  Let  us  seek 
the  causes  of  these  changes. 

In  the  air  there  float  tiny  germs  of 
a  living  plant  called  the  yeast  plant. 
When  these  germs  fall  into  sugar  and 
water  they  grow,  and  produce  great 

numbers  of  yeast  plants.     Each  yeast  .  ^ .. 

Yeast  plant  cells  (xsoo). 

plant  is  only  a  single  round  or  oval 
cell,  so  small  that  a  microscope  is  needed  to  see  it.  By  its 
growth  it  changes  the  sugar  to  alcohol  by  taking  some  car- 
bonic acid  gas  away.  But  if  there  is  a  great  deal  of  sugar 
in  the  water,  the  germs  will  not  grow  at  all.  This  is  why 
fruit  preserved  with  a  great  deal  of  sugar  keeps  so  well. 

93.  Souring.  —  If  there  is  only  a  little  sugar  in  water,  a 
smaller  germ  from  the  air  grows  with  the  yeast.     This 

ov.  PHYSIOL.  (INTER.) — 4        49 


APPLIED   PHYSIOLOGY 


changes  the  alcohol  to  vinegar,  which  makes  the  liquid 
sour.  Changing  sugar  to  alcohol  or  vinegar  is  fermenta- 
tion. All  strong  drink  contains  alcohol,  and  is  made  by 
the  fermentation  of  sugar.  Alcohol  is  sugar  with  some  of 
its  carbonic  acid  gas  taken  away. 

94.  Alcohol.  —  Alcohol  is  a  colorless  liquid  which  burns 
very  easily,  with  little  flame  and  no  smoke,  but  with  a 

great  deal  of  heat.  It  has  a  sharp, 
sweetish  taste  and  smell.  It  turns 
to  vapor  very  easily.  It  takes  water 
away  from  substances,  and  causes 
them  to  shrivel  up.  It  hardens 
albumin,  just  as  heat  hardens  the 
white  of  an  egg.  Because  it  hard- 
ens substances  and  takes  away  their 
water,  it  is  used  to  keep  things  from 
decaying.  It  is  used  for  dissolving 
many  things  which  water  would 
not  affect;  and  from  it  ether, 
chloroform,  and  numberless  other 
useful  things  are  made.  It  is  a  very  valuable  article,  and 
manufacturers  and  chemists  could  not  do  without  it.  But 
man  has  learned  that  its  taste  gives  him  pleasure,  and 
that  the  feelings  which  result  are  often  very  pleasant. 
So  day  after  day  men  drink  liquors  containing  it  for  the 
mere  pleasure  of  drinking. 

95.  Why  men  drink.  —  Men  are  ashamed  to  waste  their 
money  and  strength  in  mere  pleasure,  and  so  they  make 
excuses  for  using  the  strong  drink.     One  man  says  that  it 
warms  him,  and  another  that  it  cools  him,  and  another  that 
it  makes  him  forget  his  cares  while  he  remembers  only 
pleasant  things.     One  takes  it  to  keep  himself  awake,  and 
another  to  make  himself  sleep.     Some  take  it  to  cure  a 


Fermentation  in  a  jar  of 
cherries. 


ALCOHOL  51 

pain  or  a  cold,  and  many  drink  because  others  do.  The 
real  reason  for  drinking  alcohol  is  that  men  like  the  feel- 
ings which  it  produces  better  than  they  like  healthy  minds 
and  bodies.  Because  strong  drink  can  be  sold  for  a  great 
deal  more  money  than  it  costs,  selling  it  is  a  very  profitable 
business,  and  men  fit  up  costly  rooms  so  as  to  entice  men 
to  buy  it. 

96.  Effect  of  alcohol  upon  the  mouth.  —  Alcohol  is  a 
poison  which  has  definite  effects.     It  usually  has  effects 
opposite  to  those  that  men  think  it  has.     As  it  is  swal- 
lowed, the  alcohol  in  all  drinks  injures  the  cells  of  the  sur- 
face of   the  mouth  and  leaves  a  false  feeling  of   thirst. 
So  a  second  drink  is  taken  to  relieve  the  thirst  caused  by 
the  first.     Thus  the  drinker  keeps  on  drinking,  and  all  the 
while  grows  more  thirsty,  even  though  his  body  has  suffi- 
cient water.     His  mouth  gives  off  unpleasant  odors,  but 
this  is  due  in  part,  at  least,  to  the  coated  tongue  and  sick 
stomach  which  drink  causes. 

97.  Effects  of  alcohol  upon  the  stomach.  — In  the  stomach, 
the  alcohol  of  strong  drink  hinders  or  stops  the  action  of 
the  gastric  juice.     So  food  may  digest  more  slowly  or  pass 
into  the  intestine  without  being  changed.     The  alcohol 
also  hurts  the  mucous  membrane  of  the  stomach.     Then 
this  may  become  red  and  pour  out  a  slimy  mucus.     The 
alcohol  often  causes  a  person  to  vomit.     This  is  really  a 
good  thing,  for  so  the  stomach  gets  rid  of  the  poison. 

98.  Protection  against  alcohol.  —  When  strong   alcohol 
is  taken  into  the  mouth,  the  saliva  flows  freely  and  dilutes 
it  so  that  it  is  no  longer  capable  of  burning  the  mucous 
membrane.     This  flow  of  saliva  is  like  the  flow  of  tears  to 
wash  away  a  speck  of  dirt  from  the  eye. 

When  alcohol  reaches  the  stomach,  the  glands  in  its 
mucous  membrane  pour  out  gastric  juice  and  mucus  to 


52  APPLIED   PHYSIOLOGY 

dilute  it  just  as  the  mouth  poured  out  saliva.  If  it  were 
not  for  this  protection,  a  drink  of  strong  liquor  would 
quickly  destroy  the  stomach.  Our  bodies  can  stand  a 
great  deal  of  abuse,  because  nature  has  provided  us  with 
protection  against  all  ordinary  abuse.  Still,  after  a  time, 
the  drinking  of  alcohol  and  all  other  abuses  are  certain  to 
do  great  harm. 

99.  Digestion  of  alcohol.  —  Alcohol  itself  needs  little  or 
no  digestion.     After  it  has  been  much  diluted  by  the  fluids 
in  the  stomach  and  intestine,  it  soaks  into  the  blood  tubes 
along  with  the  food  of  the  body.    There  it  is  washed  away 
in  the  rapid  blood  stream,  so  that  not  enough  collects  at 
one  time  to  damage  the  blood  directly.     It  is  carried  to  the 
liver  and  there  disappears  at  once.     Little  or  none  can 
ever  be  found  in  the  body  beyond  the  liver.     It  is  probably 
oxidized  like  sugar,  only  very  much  more  rapidly. 

100.  Poisons  produced  by  alcohol.  —  Destroying  or  oxi- 
dizing alcohol  uses  oxygen,  so  that  there  will  be  too  little 
left  for  the  body  and  its  food.     When  a  stove  gets  too 
little  oxygen  through  its  draft,  it  produces  poisonous  smoke. 
If  the  albumin,  sugar,  and  fat  of  the  food  get  too  little 
oxygen,  they,  too,  give  rise  to  foul  substances.     These  new 
products  go  through  the  whole  body  with  the  blood,  and 
produce  far  more  poisonous  effects  than    alcohol   itself. 
Even  after  alcohol  is  destroyed,  its  harm  continues  as  great 
as  ever. 

Trying  to  use  alcohol  as  a  drink  is  like  trying  to  burn 
kerosene  in  a  coal  stove.  By  using  great  care  a  little 
kerosene  can  be  burned  without  doing  much  harm,  but  it 
smokes  and  smells  bad  and  cannot  be  controlled.  Alcohol 
behaves  like  the  kerosene.  It  gives  rise  to  poisonous  sub- 
stances, and  may  overcome  the  body  at  any  time. 

101.  How  alcohol  weakens  the  cells.  —  When  alcohol  is 


ALCOHOL  53 

used,  the  cells  are  weakened  and  poisoned  both  by  the 
alcohol  and  by  the  half-burned  albumin,  sugar,  and  fat. 
Then  they  fail  in  their  attempts  to  do  their  work.  So 
walking  is  done  in  a  staggering  way,  and  the  voice  is  thick 
and  uncertain.  A  man  in  this  condition  is  said  to  be  drunk. 
The  alcohol  may  make  him  still  weaker,  so  that  he  cannot 
stir,  but  lies  dead  drunk,  or  he  may  even  be  killed  by  the 
alcohol.  At  first  we  might  think  that  the  destruction  and 
oxidation  of  alcohol  would  develop  heat  and  force  which 
the  body  could  use.  But  it  must  be  remembered  that  the 
cells  themselves  are  made  weak,  both  by  their  lack  of  oxy- 
gen and  also  by  the  poisons  of  the  half -burned  albumin 
and  fat.  If  an  engine  is  weak  and  rusty,  a  hot  fire  under 
the  boiler  will  not  make  it  do  more  work,  but  it  may  cause 
the  whole  machine  to  be  blown  up.  A  few  men  seem 
able  to  drink  for  years,  and  yet  remain  in  fair  health.  A 
little  alcohol  will  do  great  harm  to  most  men.  At  any 
rate,  drinking  will  not  help  men  in  their  work  or  help 
them  to  live  better  lives. 

102.  Effects  of  alcohol  upon  the  liver. — The  liver  itself 
suffers  from  the  alcohol.  It  has  to  take  care  of  the  heat 
and  of  the  half-burned  albumin,  fat,  and  sugar,  and  of  all 
the  poisons  which  are  produced.  So  it  is  over-worked  and 
often  fails  in  its  duty.  Thus,  a  drinker  is  very  apt  to 
have  bilious  attacks.  If  drinking  is  kept  up  for  some 
time,  the  liver  often  wastes  away,  and  becomes  hard  and 
rough  and  unable  to  do  its  work.  Physicians  long  ago 
called  such  a  liver  a  "gin  drinker's"  liver.  When  the 
liver  has  been  harmed  in  that  way  by  alcohol,  the  body 
slowly  wastes  away,  and  finally  death  occurs  as  much  by 
starvation  as  by  poison.  Because  alcohol  disturbs  both 
the  preparation  of  the  food  of  the  cells  and  also  its  oxida- 
tion, it  affects  every  cell  in  the  body.  These  effects  will 


54  APPLIED  PHYSIOLOGY 

be  told  when  the  work  of  each  separate  set  of  cells  is 
studied. 

103.  Habit  of  drinking. — While  alcohol   is  harming  a 
man,  it  makes  him  feel  good,  so  that  he  does  not  think  of  his 
danger.    At  first  he  drinks  only  a  little,  but  it  seems  to  make 
him  feel  good.     After  it  has  gone  out  of  his  body,  he  feels 
its  harmful  effects.     Then  he  wants  another  drink,  so  as 
to  make  himself  feel  well  again.     This  desire  to  take  alco- 
hol may  compel  a  man  to  drink,  even  when  he  knows  that 
it  is  harming  him.     Strong  drink  is  like  a  man  who  visits 
at  another  man's  house,  but  is  all  the  time  robbing  him. 

104.  Laws  against  selling  alcohol.  —  If  alcohol  harmed 
only  the  body  of  the  person  who  uses  it,  it  might  not  con- 
cern any  one  except  the  drinker  himself.      But  it  does 
other  things  beside  which  the  effects  upon  the  body  are 
of  less  account.     It  takes  away  a  person's  mind  and  char- 
acter so  that  a  truthful  and  honest  man  becomes  untruthful 
and  cannot  be  trusted.      He  is  thus  very  apt  to  injure 
others,  and  even  his  dearest  friends.     Every  day  we  read 
of  drunken  husbands  beating  their  wives  and  children. 
Many  a  criminal  has  had  to  get  half  drunk  before  he  has 
dared  to  commit  his  crime.     Thus  many  have  to  suffer 
because  one  man  wants  to  have  the  pleasure  of  drinking. 
Strong  drink  harms  not  only  the  drinker,  but  also  his 
friends  and  neighbors.     So  it  is  right  to  make  laws  which 
shall  keep  a  man  from  selling  alcohol  and  strong  drink. 
School  children  are  now  learning  how  bad  alcohol  is,  and 
when  they  grow  up  they  will  know  better  than  to  use  it. 

105.  Form  of  alcohol  in  drinks.  —  The  effects  of  alcohol 
are  the  same  in  whatever  form  it  is  taken.     Pure  alcohol 
has  an  unpleasant  taste  and  burns  the  mouth  of  even  an 
old  drinker.     So  in  drinks  it  is  always  mixed  with  water. 

106.  Wine.  — We  have  seen  how  the  yeast  plant  causes 


ALCOHOL  55 

sugar  and  water  to  ferment  to  alcohol.  Fruit  juice  con- 
tains sugar  dissolved  in  the  water  of  the  juice.  The 
simplest  way  in  which  an  alcoholic  drink  is  made  is  to 
squeeze  the  juice  from  the  fruit  and  let  it  ferment  in  open 
bottles  or  barrels.  There  are  always  enough 
germs  of  the  yeast  plant  upon  the  outside 
of  the  fruit  to  start  the  fermentation,  and 
in  a  few  weeks  or  months  the  sugar  of 
the  juice  has  turned  to  alcohol.  The 
strongest  liquor  made  in  this  way  can  be 
only  one  eighth  alcohol,  for  more  than  that 
kills  the  yeast  plant.  When  grape  or  cherry 
or  blackberry  juice  is  used,  the  liquor  is 
called  wine ;  but  if  apple  juice  is  used,  it  is  called  cider. 
It  all  contains  alcohol.  Cider  begins  to  ferment  in  a 
few  hours  after  it  is  made,  and  in  a  week  it  often  has 
enough  alcohol  to  make  a  person  drunk.  In  a  short 
time  other  germs  enter  the  cider  and  change  the  alcohol 
to  vinegar.  Homemade  wine  contains  alcohol,  and  its 
use  is  as  harmful  as  though  it  were  bought  at  the  saloon. 
Some  wine  has  pure  alcohol  added  to  it  to  make  it  keep 
better. 

Since  wine  is  made  of  fruit  juice,  it  may  contain  some 
albumin,  which  is  of  value  as  food,  but  to  buy  wine  is  a 
very  expensive  way  to  buy  albumin,  and  besides  the  albu- 
min of  wine  is  not  nearly  so  good  as  the  albumin  of  bread 
or  meat.  Wine  may  contain  some  unfermented  sugar  also. 

The  flavor  of  wine  depends  upon  the  kind  of  fruit  and 
the  amount  of  fermentation.  It  has  little  to  do  with  the 
amount  of  alcohol  in  the  wine.  Fermented  fruit  juice 
was  the  only  kind  of  alcoholic  drink  which  people  knew 
in  ancient  times.  It  was  weak  in  alcohol,  and  a  great  deal 
was  needed  to  make  a  man  drunk.  Much  of  the  wine 


APPLIED   PHYSIOLOGY 


What  beer 
contains. 


which  we  read  about  in  the  Bible  was  fresh  grape  juice 
used  before  fermentation  had  begun. 

107.  Beer.  —  The  alcoholic  drink  which  is  most  used  is 
beer.  Beer  is  made  chiefly  from  barley.  The  grain  is 
moistened,  and  each  seed  begins  to  grow.  This  turns  the 
starch  of  the  grain  to  sugar.  When  the  sprouts  are  about 
half  an  inch  in  length,  the  grain  is  dried. 
This  dried  grain  is  called  malt.  The  malt  is 
boiled  in  water  so  as  to  dissolve  the  sugar. 
The  liquor  is  strained  off,  and  hops  and  other 
flavoring  matters  are  put  in.  Then  yeast 
is  added,  for  the  boiling  kills  the  yeast 
which  was  there  at  first.  Fermentation 
takes  place  and  changes  the  sugar  to  alco- 
hol. Beer  is  about  one  twentieth  alcohol, 
but  some  is  a  great  deal  stronger.  Beer,  like  wine,  con- 
tains some  albumin,  but  the  best  beer  or  ale  has  little  of 
the  food  part  of  the  grain  of  which  it  is  made.  Some 
men  drink  three  or  four  quarts  of  beer  a  day.  This 
makes  them  fat,  but  it  does  not  give  them  strength. 

Root  beer  is  made  at  home  by  boiling  aromatic  roots  and 
leaves  with  molasses  and  adding  yeast  to  the  liquor.     The 
molasses  ferments  and  becomes  alcohol.     All 
root  beer  has  alcohol  in  it. 

108.  Distilled  liquors.  —  When  a  pot  of 
alcohol  and  a  pot  of  water  are  set  upon  a 
stove  together,  the  alcohol  begins  to  boil 
much  sooner  than  the  water,  and  is  sooner 
turned  to  vapor.  If  water  and  alcohol  are 
mixed  together  and  heated,  the  alcohol  makes 
the  largest  part  of  the  vapor,  and  is  at  last 
driven  off  before  half  the  water  is  gone.  If  this  vapor 
is  collected  and  cooled,  it  becomes  a  liquid,  and  con- 


What  whisky 
contains. 


ALCOHOL  57 

tains  far  more  alcohol  than  the  first  liquor.  If  this 
liquor  is  boiled  over  and  over  again,  the  alcohol  is  fur- 
ther separated  from  the  water  until  it  is  almost  pure. 
Separating  alcohol  from  water  by  heating  is  called  distilla- 
tion. Many  liquors  are  made  by  distillation.  If  wine  is 
distilled,  the  liquor  is  called  brandy,  but  if  grain  is  used  to 
make  the  alcohol,  it  is  called  whisky.  Brandy  and  whisky 
are  each  about  one  half  alcohol.  When  first  made  they 
contain  a  very  poisonous  kind  of  alcohol.  They  are  both 
kept  for  months,  and  even  years,  before  being  used,  so  as 
to  change  this  more  poisonous  alcohol  to  common  alcohol. 

109.  History  of  strong  drink.  —  The  germs  of  yeast  grow 
almost  everywhere.  By  their  growth  alcohol  is  always 
formed  wherever  fruit  decays  or  its  juice  has  an  oppor- 
tunity to  collect.  For  thousands  of  years  men  have  known 
the  taste  and  the  effects  of  fermented  liquors,  and  how  to 
produce  the  fermentation.  Almost  every  known  race  of 
men  has  made  wine  from  the  earliest  times.  Noah  made 
wine  shortly  after  the  flood,  and  wine  is  mentioned  in 
many  places  in  the  Bible.  In  the  earliest  recorded  times 
people  of  Egypt  and  of  Assyria  used  wine  on  their  tables 
and  often  made  themselves  drunk.  The  native  Mexicans 
had  an  intoxicating  liquor  when  the  Spaniards  came  in  the 
early  part  of  the  sixteenth  century.  But  the  ancients  never 
used  drink  so  strong  as  it  is  made  now,  for  fermentation 
stops  .when  the  juice  becomes  one  eighth  alcohol. 

About  eight  hundred  years  ago  the  professors  in  the 
colleges  and  all  other  learned  men  of  the  time  were  look- 
ing for  three  impossible  things.  They  were  trying  to  find 
out  by  the  stars  what  would  take  place  in  times  to  come. 
This  study  led  to  our  knowledge  of  astronomy. 

They  were  trying  to  discover  how  to  change  common 
metals  to  gold.  By  their  mixing  and  dissolving  all  kinds 


58  APPLIED  PHYSIOLOGY 

of  substances  they  built  up  the  beginning  of  chemistry, 
and  discovered  many  things  about  wine  and  spirits. 

Above  all  things,  men  of  eight  hundred  years  ago  were 
seekers  for  a  substance  which  would  make  the  old  young 
again  and  prevent  the  young,  from  growing  old.  They 
believed  that  there  was  really  such  a  substance  existing  in 
the  form  of  a  very  light  spirit  or  gas.  So  they  boiled  sub- 
stances in  order  to  collect  their  gases.  When  wine  was 
boiled  they  obtained  a  new  substance  which  we  know  as 
alcohol. 

A  famous  Arabian,  named  Albucasis,  drank  some  of  the 
alcoholic  liquor  which  he  had  made  and  which  was  really 
brandy.  He  at  once  seemed  to  be  a  young  and  joyful 
man  again.  He  told  of  his  wonderful  discovery,  and  by 
means  of  his  so-called  "  water  of  life,"  he  brought  back  the 
joys  of  youth  to  other  old  men.  They  soon  discovered 
their  mistake,  but  found  themselves  enslaved  by  the  habit 
of  taking  the  poisonous  liquor.  Soon  all,  including  Albu- 
casis himself,  died  from  the  effects  of  the  strong  drink. 
Before  their  time  men  had  become  drunk  and  had  died 
from  the  effects  of  wine;  but  the  effects  of  the  distilled 
liquor  were  far  more  rapid  and  deadly  than  anything  which 
they  had  known  before.  To-day  men  drink  as  much 
brandy  and  whisky  as  they  do  wine. 

Within  the  last  few  years  men  have  found  out  how  to 
make  strong  drink  quickly  and  cheaply.  To  do  this,  how- 
ever, they  must  either  add  poisons  or  else  neglect  to 
remove  some  which  are  always  found  in  new  liquor.  Yet 
no  one  can  tell  the  poor  liquor  from  that  which  is  old  and 
pure.  Any  strong  drink  is  poisonous;  but  much  of  the 
cheap  liquor  to-day  is  as  much  more  dangerous  than  the 
whisky  of  fifty  years  ago  as  that  was  more  poisonous 
than  the  wine  of  old. 


ALCOHOL  59 

SUMMARY 

1.  Alcohol  is  made  from  sugar  by  the  growth  of  the  yeast 

plant.  In  the  body  it  needs  no  digestion,  but  it  hin- 
ders the  digestion  of  other  things.  It  enters  the 
blood  at  once,  but  quickly  disappears  again. 

2.  The  use  of  alcohol  tends  to  make  men  drink  even  when 

they  feel  that  it  will  harm  them. 

3.  Its  oxidation  uses  up  oxygen,  so  that  too  little  is  left 

for  the  albumin,  sugar,  and  fat.  Half-burned  and 
poisonous  substances  are  produced  by  their  oxidation 
like  the  gases  from  a  smoking  lamp. 

4.  These  poisons  and  the  lack  of  oxidation  in  the  cells  of 

the  body  weaken  the  cells. 

5.  Alcohol  makes  the  liver  smaller  and  harder. 

6.  The  three  different  kinds  of  alcoholic  drinks  are  wine, 

beer,  and  distilled  liquors. 

7.  All  fermented  drinks  contain  alcohol,  and  so  are  forms 

of  strong  drink. 


CHAPTER   VII 
THE  BLOOD  AND  ITS   CIRCULATION 

110.    The  blood.  —  After  the  food  has  been  digested  in 

the  stomach  and  intestine  and  made  into  blood   in  the 

liver,  it  is  sent  to  feed  each  cell  of  the  body.     About  one 

I  thirteenth  of  a  man's  body  is  blood.     This  makes  between 

five  and  six  quarts. 

The  blood  is  a  red  liquid,  but  under  a  microscope  it 
looks  like  clear  water  in  which  there  float  a  great  many 

*mimwm       round   bodies-       Most   of    these    bodies 

wjuiunniiiiiiimiif))!  ..  .  11     i          r    r  7       T         7/ 

©  (5)  ©  ©  /®v       are  rec*>   anc*    are    caUed  re<*   blood  cells 


©      tf@©       or  corpuscles;    a  few  are  white,  and  are 
c  o  t>   (3>  ©          called  white  blood  cells  or  corpuscles. 

B100(dXC°4?oU)SCleS  1U-    The  bl°°d  CellS'  ~  EaCh  rCd  bl°°d 

aapileTredblood      Cel1    is    a    rOUnd>    flat   Plate«       Jt    d°es    nOt 

cells.  feed  the  cells  of  the  body,  but  supplies 

b  refla^w°sde.CellSSeen  them  with  oxygen  from  the  air  in  the 
c  red  blood  cells  seen  lungs.  The  red  cells  form  nearly  one 
d  whtegb7ood  cells.  half  of  the  blood. 

Each  white  blood  cell  is  round  like  a 
ball.  It  moves  with  the  blood,  but  it  can  move  all  by 
itself  and  live  outside  the  blood.  It  is  almost  a  living 
being  in  the  blood,  separate  from  the  body.  The  white 
blood  cells  are  only  one  three-hundredth  as  numerous  as 
the  red  cells.  They  are  always  looking  for  weak  or  in- 
jured parts  of  the  body,  and  when  they  find  such  a  spot 
they  leave  the  blood  tubes  and  gather  around  it  to  mend 

60 


THE    BLOOD  AND   ITS   CIRCULATION 


61 


it.  They  also  surround  and  destroy  poisons  which  happen 
to  get  among  the  cells.  We  will  speak  of  this  later  when 
we  talk  of  inflammation  and  of  catching  cold.  (See  §  137.) 

112.  Plasma.  —  The  liquid  part  of  the  blood  is  called 
plasma.     It  is  water,  in  which  a  little  albumin  and  mineral 
matters  are  dissolved.     The  albumin  and  the  mineral  mat- 
ters are  the  real  food  of  the  cells. 

When  blood  is  drawn  from  the  body,  it  soon  becomes 
like  jelly,  or  it  clots,  as  we  say.  In  clotting,  some  of  the 
.albumin  of  the  plasma 
becomes  hard  like  a  boiled 
egg  and  makes  the  whole 
blood  like  jelly.  Soon 
the  clot  begins  to  grow 
smaller  and  to  squeeze 
out  the  liquid  parts  of 
the  blood.  Then  the 
clot  will  float  in  a  straw- 
colored  liquid  called 
serum.  In  a  cut  a  clot 
reaches  into  the  mouth 
of  each  blood  tube  and 
stops  the  opening,  so 
that  no  more  blood  can 
ing  is  stopped. 

113.  Arteries.  —  The  blood  is  carried  to  the  cells  of  the 
body  through  tubes  which  branch  and  divide  again  and 
again,  until  they  reach  every  part  of  the  body.     The  tubes 
which  carry  blood   to   the  cells  of   the    body  are    called 
arteries.     Their  sides  are  strong  and  tight,  so  that  they 
cannot   burst  or  leak.     In  them  are  muscles  which  can 
make  them  larger  or  smaller,  so  as  to  let  the  right  amount 
of  blood  pass  through  for  the  use  of  the  cells  of  the  body. 


Arrangement  of  capillaries. 


a  smallest  artery. 

b  smallest  vein. 

c  network  of  capillaries. 

flow.     This  is  the  way  all  bleed- 


62 


APPLIED   PHYSIOLOGY 


114.  Capillaries.  —  The  end  of  each  artery  divides  into  a 
number  of  fine  tubes  called  capillaries.  The  capillaries 
make  a  network  so  fine  that  they  touch  every  cell  of  the 
body.  The  point  of  a  needle  cannot  prick  the  skin  with- 
out bursting  some  of  the  capillaries  and  so  drawing  blood. 
Each  capillary  has  sides  so  thin  and  soft  that  the  liquid 

parts  of  the  blood  easily 
soak  through  to  reach  the 
cells,  and  even  the  white 
blood  cells  burrow  through 
its  sides  without  harming 
the  tube.  The  capillaries 
are  only  just  large  enough 
to  let  the  blood  cells 
pass  through. 

115.  How  to  see  the 
capillary  circulation.  — 
The  web  of  a  frog's  foot 
is  very  thin  and  clear,  and  yet  contains  many  capillaries. 
If  it  is  spread  out  untler  a  microscope,  you  can  see 
the  blood  as  it  shoots  through  the  tiny  tubes.  You  can- 
not see  the  liquid  part,  for  it  is  like  water,  but  you  will 
see  the  red  blood  cells,  which,  in  the  frog,  are  egg-shaped. 
They  will  pass  through  the  larger  tubes  in  a  stream  too 
rapidly  for  you  to  see  the  separate  cells.  In  the  smallest 
tubes,  a  cell  may  get  stuck  crosswise  for  a  moment  and 
stop  up  the  whole  tube,  but  it  soon  becomes  free  again 
and  passes  on.  Sometimes  a  cell  starts  to  go  through, 
when  a  little  movement  of  the  leg  will  press  it  back  again. 
You  should  get  your  teacher  or  some  physician  to  show 
you  this  circulation.  This  will  help  you  to  remember 
that  millions  of  these  tiny  streams  are  continually  flowing 
through  every  part  of  your  body. 


Diagram  showing  how  food  reaches  the 
cells  from  the  capillaries. 


THE  BLOOD  AND   ITS  CIRCULATION 


116.  Veins.  —  The  capillaries  come  together  again  and 
form  tubes  called  veins.     Each  vein  is  a  tube  much  like 
an  artery.     It  carries  blood  away  from  the  cells.     It  has 
valves  which  permit  blood  to  flow  toward  the  heart  but 
keep  it  from  flowing  back  to  the  cells.     Each  vein  runs  by 
the  side  of  the  artery  which  brought  the  blood  to  it.     So 
the  blood  tubes  are  like 

a  net  hanging  from  two 
ropes.  One  rope  is  an 
artery,  the  net  is  the 
capillaries,  and  the  other 
rope  is  the  vein.  The 
blood  is  always  moving 
in  the  tubes.  We  must 
find  out  what  moves  it. 

117.  The     heart.  —  If 
we    follow    the    arteries 
back,  we  shall  see   that 
they  unite  and  grow  larger 
until  we  reach  a   single 
tube      nearly    an       inch 

through.       This    artery   is    c  closed  valve  to  keep  blood  from  flowing 
.        ,  back  into  the  auricle. 

called  the  aorta.     At  the   4  ventricle. 
beginning  of  the  aorta  is   e  arterv- 

/  valve  to  keep  blood  from  returning  to  the 

a  pump  called  the  heart.         ventricle. 
The  heart  lies  just  to  the    • 

left  of  the  middle  of  the  body,  and  just  below  the  level 
of  the  armpits.  It  is  a  bag  about  the  size  of  the  fist. 
Its  inside  is  divided  so  as  to  make  two  bags.  Each  bag 
is  a  complete  pump.  The  lower  part  of  each  side  of  the 
heart  is  called  a  ventricle,  and  the  upper  part  an  auricle. 
There  are  two  openings  in  each  ventricle.  A  hole  in 
its  upper  part  leads  to  the  auricle.  It  can  be  closed 


Diagram  of  the  heart  while  it  is  beating. 

a  vein  entering  the  auricle. 
b  auricle. 


64  APPLIED   PHYSIOLOGY 

tightly  by  two  curtains.  A  hole  in  its  side  opens  into  an 
artery. 

When  the  ventricle  is  full  of  blood,  all  at  once  it  becomes 
smaller  and  squeezes  the  blood.  The  pressure  closes  the 
opening  to  the  auricle  and  keeps  the  blood  from  going  out 
that  way,  and  so  it  passes  into  the  artery.  Three  little 
curtains  keep  it  from  running  back  into  the  ventricles. 
The  heart  keeps  the  arteries  full  of  blood,  and  presses 
it  through  their  branches  and  through  the  capillaries  and 
veins.  It  finally  reaches  the  heart  again  and  flows  into 
the  auricles.  Then  it  flows  into  the  ventricles  again,  ready 
for  another  round  of  the  body. 

The  sides  of  the  auricles  are  thin,  for  they  are  made 
only  to  hold  the  returning  blood  while  the  ventricles  are 
squeezing  blood  into  the  arteries. 

118.  Why  the  heart  is  double.  —  The  left  part  of  the 
heart  sends  blood  to  all  parts  of  the  body  to  nourish  its 
cells.     The  right  half  of  the  heart  sends  the  blood  only 
to  the  lungs.     There  the  blood  gets  air,  which  it  carries  to 
the  cells.     Food  is  gathered  from  the  intestine  by  blood 
which  is  pumped  by  the  left  half  of  the  heart,  but  in  man 
only  the  right  half  of  the  heart  sends  blood  to  get  air. 
A  fish  has  only  one  auricle  and  one  ventricle,  which  send 
blood  to  get  both  air  and  food. 

119.  Course  of  the  circulation.  — The  left  half  of  the  heart 
sends  blood  through  the  arteries  to  all  parts  of  the  body. 
They  empty  it  into  the   capillaries.     Here  some  of  the 
plasma  and  air  go  out  to  feed  the  cells.      The  rest  of 
the  blood  then  enters  the  veins,  which  bring  it  back  to  the 
heart,    where   it   enters   the   right   auricle   and   ventricle. 
They  send  it  to  the  lungs  to  get  air.     Then  it  returns  to 
the  left  auricle  and  ventricle  ready  for  another  round  of 
the  body.      It  takes  twenty  seconds  to  send  a  drop  of 


THE    BLOOD   AND   ITS   CIRCULATION 


blood  through  the  left  ventricle,  then  through  the  arteries, 
capillaries  and  veins,  and  then  to  the  lungs  and  back  to 
the  left  ventricle. 
All  the  blood  in 
the    body   passes 
through  the  heart 
every    two     min- 
utes. 

120.  Venous 
and  arterial  blood. 
—  In  the  lungs 
the  blood  from 
the  veins  be- 
comes of  a 
bjrj  2Lb^e-r  red 
color.  It  goes 
back  to  the  heart 
and  is  sent  out 
again  by  the  ar- 
teries. The  blood 
going  to  the  cells 
of  the  body  is  of 
a  bright  red  color 
and  is  called  ar- 
terial blood.  The 
blood  as  it  comes 
from  the  cells  is 
darker  in  color 
and  is  called  ve-. 
nous  blood.  Ve- 
nous blood  is  not 

bad  blood,  but  the  change  is  due  merely  to  the  decrease 
in  the  amount  of  air  in  the  blood, 
ov.  PHYSIOL.  (INTER.)  —  5 


Diagram  of  the  course  of  the  blood  in  the  circulation. 


66  APPLIED    PHYSIOLOGY 

121.  The  heart  beats  and  pulse.  —  While  the  heart  is 
squeezing  the  blood,  it  can  be  felt  through  the  sides  of  the 
body ;  this  is  called  a  heart  beat.     Each  heart  beat  makes 
a  wave  of  blood  in  the  artery  which  can  be  felt  when  the 
artery  is  near  the  skin.     This  wave  is  called  a  pulse  and  is 
best  felt  in  the  wrist.     The  heart  beats  about  seventy-five 
times  each  minute.     Running  or  other  work  of  any  kind 
makes  it  beat  faster,  so  as  to  send  more  blood  to  the  cells 
which  are  working. 

122.  How  cells  eat.  —  Let  us  learn  exactly  how  the  cells 
of  the  body  eat.     We  have  seen  how  albumin  and  mineral 
matters  soak  through  the  sides  of  the  capillaries  along 
with  the  liquid  parts  of  the  blood,  so  as  to  reach  the  cells 
of  the  body.     Each  cell  is  thus  bathed  in  food,  and  eats 
by  soaking  it  in  from  all  sides.     So  each  cell  is  like  the 
ameba,  but  with  these  differences : 

First.  The  ameba  must  seek,  catch,  and  digest  its 
food,  while  the  cells  of  the  body  are  always  soaked  in  food 
ready  for  their  instant  use.  A  few  cells  of  the  body  in 
the  stomach,  the  liver,  the  heart,  and  the  blood  tubes  do  all 
the  work  of  making  the  food  ready  for  the  rest  of  the  cells. 

Secondly.  The  ameba  can  move  about,  while  the  only 
cells  of  the  body  which  can  move  about  are  the  white 
blood  cells.  The  rest  are  held  in  place  by  little  strings 
called  connective  tissue. 

Thirdly.  The  ameba  does  just  what  it  wants  to,  while 
the  cells  of  the  body  each  have  one  kind  of  work  to  do 
and  must  obey  the  orders  of  the  mind  in  doing  it. 

Besides  eating,  each  cell  takes  air  from  the  blood  and 
gives  off  carbonic  acid  gas  and  water  and  other  waste 
matter  from  every  side.  Thus  each  cell  breathes.  We 
shall  see  how  it  breathes  when  we  study  the  lungs. 

123.  The  lymph.  —  The  cells  cannot  eat  all  the  plasma 


THE  BLOOD   AND   ITS  CIRCULATION  67 

which  soaks  through  the  capillaries,  and  so  some  always 
surrounds  the  cells.  White  blood  cells  also  go  through  the 
sides  of  the  capillaries  and  live  between  the  cells  of  the 
body.  Each  cell  also  gives  off  waste  matter.  The  mix- 
ture of  these  matters  makes  a  fluid  called  lympk,  which  is 
always  bathing  the  cells.  Lymph  is  thin  blood  without 
its  red  cells.  Only  a  little  lymph  can  go  back  to  the 
capillaries ;  so  to  take  away  the  rest  there  is  another  set 
of  tubes  called  lymphatics. 

124.  Lymphatics.  —  Each  lymphatic  is  like  a  small  capil- 
lary with  thin  walls.     It  begins  in  spaces   between  the 
cells  and  carries  away  the  lymph,  just  as  a  pump  driven 
deep  into  the  wet  earth  brings  up  water.      The  smaller 
lymphatics  unite  to  form  about  twenty  fine  tubes  for  each 
limb.     They  are  too  small   and   thin  to   be   easily  seen. 
They  run  up  the  limb,  and  at  the  backbone  join  together 
to  form  a  single  tube  about  the  size  of  a  quill.     This  tube 
is  called  the  thoracic  duct.     It  opens  into  a  large  vein  in 
the  neck.     Thus  the  matters  which  leak  out  of  the  capil- 
laries return  to  the  blood  in  a  roundabout  way.     Digested 
fat  also  reaches  the  blood  through  the  lymphatics.     The 
lymphatics  are  really  a  third  set  of  blood  tubes. 

125.  Lymph   nodes.  —  Here  and  there   the   lymphatics 
pass  through  little  bodies  like  grains  of  wheat  or  corn. 
They  can  be  felt  under  the  lower  jaw  and  in  the  groin, 
and  are  called  lymph  nodes.     Each  node  is  like  a  sponge 
filled  with  white  blood  cells.     As  the  lymph  flows  through 
the  nodes  they  strain  out  and  keep  back  poisons  and  waste 
matters  which  the  white  blood  cells  eat  and  destroy.     So 
these  nodes  protect  the  body  against  poisoning.     In  some 
diseases   they   get   so   full   of   poison   that   they   become 
swollen,  red,  and   painful.     In  scrofula  the  nodes  in  the 
neck  often  form  large  swellings  from  this  cause. 


68  APPLIED    PHYSIOLOGY 

126.  Regulation  of  the  flow  of  blood.  —  When  a  cell  is 
working  hard,  it  needs  more  food  than  when   it  is  still. 
Nature  provides  more  food  for  a  working  part  in  two  ways : 

First.  The  muscles  in  the  arteries  relax,  so  that  the 
tubes  become  larger.  Then  more  blood  flows  through  the 
part.  When  you  run,  your  face  looks  red  from  this  cause. 

Second.  The  heart  itself  beats  faster  and  with  greater 
strength.  After  a  race  you  can  feel  your  heart  beat 
within  your  chest  In  these  two  ways  nature  always  pro- 
vides the  exact  amount  of  food  which  each  part  needs. 

127.  Effects  of  too  much  exercise.  —  During  severe  work 
the   heart   works    harder,  so    as   to  provide  food  for  the 
cells.     This  soon  wears  out  the  heart,  so  that  it  cannot 
send  enough  blood  even  for  light  work.     Boys  can  run  or 
work  as  hard  as  they  please  for  a  minute  or  two  at  a  time 
and  will  not  be  harmed.     But  they  often  try  to  see  which 
one  can  run  the  farthest  or  lift  the  most.     Then  they  may 
get  very  tired  and  may  so  weaken  their  hearts  that  they 
never  recover. 

128.  Fainting.  —  When  the  heart  beats  with  little  force, 
or  stops  beating,  the  cells  suffer  at  once.     The  brain  suf- 
fers sooner  than  any  other  part.     Then  the  mind  stops 
acting,  and  the  person  is  faint.     His  face  is  white,  for  it 
has  no  blood,  and  he  is  in  a  deep  sleep. 

When  a  person  faints,  lay  him  down  with  his  head  low, 
so  that  blood  will  go  to  the  brain.  Rub  his  arms  and  legs 
towards  his  body  to  drive  the  blood  to  his  heart.  Also 
throw  cold  water  on  his  face  to  cause  the  heart  to  beat 
harder.  In  a  moment  or  two  he  will  revive  and  be  as  well 
as  before. 

129.  Alcohol  and  blood.  —  Alcohol  hinders  the  digestion 
of  food  and  weakens  the  liver  so  that  it  cannot  change 
the  food  to  blood  as  it  should.     Thus  the  blood  carries  too 


THE   BLOOD  AND   ITS  CIRCULATION  69 

little  food  to  the  cells.  Men  who  drink  become  thin  and 
weak.  But  beer  drinkers  take  a  great  amount  of  water 
in  the  beer,  and  this  makes  them  heavy  and  large.  They 
look  fat  and  healthy,  but  there  is  little  strength  in  their 
flesh. 

When  alcohol  takes  oxygen  from  the  body,  the  real  food 
is  half  burned.  The  poisons  which  are  produced  remain 
in  the  blood  and  are  carried  to  the  cells  and  still  further 
weaken  them.  So  the  drinking  man  can  be  injured  by 
causes  which  would  have  no  effect  upon  him  if  he  did  not 
drink.  It  is  not  true  that  alcohol  helps  any  one  to  resist 
disease ;  the  truth  is  that  the  drinker  is  very  liable  to  be- 
come sick.  * 

130.  Alcohol  and  the  arteries. — The  oxidation  of  alcohol 
makes  a  large  amount  of  heat  suddenly.     To  get  rid  of 
it  the  muscles  of  the  arteries  suddenly  loosen  and  let  the 
tubes  become  larger.     So  more  blood  flows  through  to  the 
capillaries.     This  happens  in  the  skin  more  than  anywhere 
else,  and  so  more  blood  touches  the  air  and  the  heat  is 
lost.     When  the  arteries  have    often  been  made  larger, 
their  muscles  lose  the  power  of  acting,  and  so  they  remain 
too  large  permanently.     After  a  while  a  drinker's  face  and 
nose  are  red  all  the  time.     If  his  flesh  is  cut,  an  extra 
amount  of  blood  is  needed   to    heal   the  cut;   when  the 
arteries   cannot   regulate   the   amount   of   blood,  the   cut 
heals  slowly.     If  any  part  of  the  body  is  diseased,  the 
extra  quantity  of  blood  cannot  be  sent  to  the  part,  and  so 
it  gets  well  slowly.     During  sickness  or  a  surgical  opera- 
tion a  drinker  is  always  in  greater  danger  of  his  life  than 
he  would  have  been  if  he  had  let  drink  alone. 

131.  Alcohol  and  the  heart. — Alcohol  acts  as  a  stimulant, 
and  compels  the  cells  of  the  body  to  do  more  work ;  but 
gives  them  no  extra  strength  with  which  to  do  it. 


7O  APPLIED   PHYSIOLOGY 

The  heart  is  the  most  regular  and  the  best  behaved 
organ  in  the  body,  but  alcohol  makes  it  beat  faster  and 
harder  than  the  body  needs.  So  it  tires  itself  out,  and 
soon  its  beats  become  weaker.  Thus  a  strong  man  weak- 
ens his  heart  instead  of  making  it  stronger.  The  cells  of 
the  heart's  muscle,  like  the  rest  of  the  cells  of  the  body, 
do  not  get  proper  food,  and  so  they  become  still  weaker. 
Alcohol  gives  a  feeling  of  great  strength  to  the  body,  but 
this  is  due  to  weakness  of  the  brain,  which  does  not  feel 
fatigue  as  it  should. 

132.  Tobacco.  —  Tobacco  weakens  and  poisons  all  the 
cells  of  the  body,  but  it  affects  the  heart  more  than  any 
other  part.  It  causes  the  heart  to  beat  more  rapidly,  and 
at  the  same  time  with  less  strength.  Sometimes  the  heart 
beats  slower  than  it  should  for  a  little  while,  and  then 
becomes  rapid  again.  Sometimes  its  beat  can  be  too 
plainly  felt.  The  result  is  that  the  smoker  cannot  work 
so  hard  as  he  once  could.  His  heart  beats  with  violence, 
but  drives  the  blood  with  little  force.  He  becomes  very 
short  of  breath,  because  the  blood  does  not  circulate  in 
the  lungs  as  it  should.  When  a  young  person's  heart  is 
injured  by  tobacco,  there  is  great  danger  that  it  will  stay 
weak  all  through  life.  Athletes,  when  training  for  a  con- 
test like  running  or  rowing,  do  not  smoke  or  chew,  for 
they  know  that  to  do  so  would  weaken  their  hearts  and 
make  them  short-winded. 

SUMMARY 

1.  The  blood  is  a  clear  liquid  containing  albumin  and 

minerals.    In  it  there  float  many  red  cells  and  fewer 
white  cells. 

2.  Tubes  called  arteries  carry  blood  to  all  parts  of  the 

'  body. 


THE  BLOOD   AND   ITS  CIRCULATION  7 1 

3.  Fine  tubes  called  capillaries  receive  the   blood  and 

give  it  out  to  the  cells. 

4.  Other  tubes  called  veins  carry  the  blood  back  to  the* 

heart. 

5.  The  heart  is  a  pump  which  keeps  the  blood  in  motion. 

6.  Each  stroke  of  the  heart  makes  a  wave  in  the  arteries, 

which  we  can  feel  as  the  pulse. 

7.  Cells  eat  the  albumin  and  minerals  which  pass  out  of 

the  capillaries,  taking  the  food  in  by  any  part  of 
their  bodies. 

8.  The  food  which  the  cells  do  not  use  drains  off  in  a  set 

of  tubes  called  lymphatics,  which  finally  empty  into 
a  vein  near  the  heart. 

9.  When  a  part  needs  more  blood,  the  arteries  become 

enlarged,   and  the  heart  pumps  harder,   so  as   to 
carry  more  to  it. 

10.  Alcohol   makes   the   arteries   larger   and   causes  the 

heart  to  beat  quickly. 

11.  Tobacco  poisons  the  muscle  of  the  heart. 


CHAPTER   VIII 
BLEEDING,   WOUNDS,   AND  DISEASE  GERMS 

133.  Bleeding. — When  a  person  loses  much  blood,  he 
feels  weak  and  faint,  and  if  one  half  the  blood  is  lost,  he 
dies.     So  bleeding  is  dangerous  to  life.     We  have  seen 
how  the  blood  clots  and  stops  bleeding.     When  a  large 
artery  is  cut,  the  force  of  the  blood  drives  the  clot  out  as 
fast  as  it  forms,  and  so  there  is  great  danger  of  bleeding 
to  death.     Blood  from  a  cut  artery  spurts  out ;  blood  from 
a  cut  vein  only  flows  out,  and  does  not  spurt.     So  bleeding 
from  an  artery  is  far  more  dangerous  than  from  a  vein. 

134.  How.  to  stop  bleeding.  —  Every  one  should  know 
how  to  stop  bleeding.     When  dangerous  bleeding  occurs, 
just  squeeze  the  sides  of  the  wound  tightly  together  with 
your  hands.     This  is  a  sure  and  safe  way  of  stopping  any 
bleeding  until  some  one  comes  who  can  help  you.     But 
sometimes  a  cut  must  be  held  for  hours  before  enough 
clot  is  formed  to  stop  bleeding.     So  while  you  are  holding 
the  cut  you  can  get  a  handkerchief  or  any  piece  of  cloth 
ready  so  as  to  tie  it  tightly  over  the  cut,  or  just  above  it. 
Then    a  stick  may  be   put  under  the   handkerchief  and 
twisted  tightly,  so  as  to  close  the  bleeding  artery.     There 
is  one  important  thing  to  remember :  keep  everything  as 
clean  as  possible,  and  put  no  earth  or  cobwebs,  or  any 
other  dirty  thing  upon  the  cut,  for  there  is  great  danger 
of  poisoning  the  wound  by  it.     If  bleeding  comes  from 
the  arm  or  leg,  very  much  less  blood  will  go  to  the  limb  if 

72 


BLEEDING,   WOUNDS,  AND   DISEASE  GERMS 


73 


the  person  lies  down  and  holds  the  limb  straight  up  in  the 
air.  In  nosebleed,  the  person  should  sit  up  so  that  the 
blood  will  not  run  to  the  head.  If  he  presses  the  nostrils 
together  and  breathes  through  his  mouth,  the  bleeding  will 
soon  stop.  Then  he  should  not  blow  the  nose  for  some 
time,  so  that  the  clot  may  have  time  to  get  thick  and 
surely  stop  the  bleeding. 

135.  Injury  to  cells.  —  The  cells  of  the  body  are  always 
likely  to  be  hurt,  and  yet  they  quickly  mend  themselves 
again.      They   are    hurt   by   cuts,    scratches,    burns,    and 
bruises.     A  blast  of  cold  air  upon  a  heated  part  of  the 
body  hurts  the  cells.     But  wounds  are  soon  mended  if  we 
do  not  take  cold  in  them.     We  must  explain  what  taking 
cold  is. 

136.  Bacteria  of  disease.  —  There  are  tiny  living  beings 
called   bacteria  which  grow  everywhere  in  dead  matter. 
They     produce     decay, 

and  change  dead  bodies 
to  a  form  which  plants 
can  use  as  food.  With- 
out them,  dead  bodies 
would  accumulate  and 
cover  the  earth.  But 
a  few  kinds  can  live  in 
the  lymph  between  the 
capillaries  and  the  cells 
of  the  body,  and  there 
produce  diseases.  A 
few  of  these  seeds  or 
germs  of  disease  are 
everywhere  in  the  air, 

water,  and  soil,  but  there  are  very  many  in  all 'kinds  of 
dirt  and  filth.  A  pin  point  can  carry  thousands  of  these 


Bacteria  growing  in  the  mouth  ( x  400) . 

The  specimen  was  obtained  by  scraping  a 
healthy  mouth. 

a  nucleus  of  an  epithelial  cell. 
b  different  forms  of  bacteria. 
c  outline  of  an  epithelial  cell. 


74 


APPLIED   PHYSIOLOGY 


germs  into  the  skin.  They  seldom  grow  in  the  blood,  for 
it  is  in  too  rapid  motion,  but  they  do  grow  in  the  lymph 
and  produce  millions  of  new  bacteria.  They  may  fall  upon 
a  sore  spot,  or  a  cut,  and  so  go  into  the  lymph  at  once. 
These  bacteria  live  upon  the  lymph  and  give  out  poisons 
which  may  make  the  whole  body  sick.  Typhoid  fever, 
diphtheria,  cholera,  and  erysipelas  are  kinds  of  sickness 
caused  by  the  bacteria.  When  a  cut  discharges  matter, 
it  is  due  to  the  same  thing.  The  growth  of  these  germs, 
and  the  effect  of  the  poisons  which  they  make,  is  what  is 
usually  meant  by  "taking  cold." 

Bacteria  are  always  ready  to  enter  the  lymph,  and  the 
object  of  the  physician  and  surgeon  is  to  keep  them  out. 

^ _____   . When    the    germs    are 

a 


kept  out,  heat  and  cold 
and  wet  will  not  make 
a  person  take  cold  in  a 
cut  or  wound  of  any 
kind. 

137.  Inflammation.  — 
Whenever  the  body  is 
hurt,  the  first  thing  it 
does  towards  mending 
the  wound  is  to  loosen 
the  muscles  of  the  arte- 
ries going  to  the  hurt 
spot,  so  as  to  let  more 
blood  go  there.  This  makes  the  part  red.  Then  the 
white  blood  cells  begin  to  stick  to  the  sides  of  the  finest 
blood  tubes  and  to  pass  through  their  sides  into  the 
lymph  spaces.  At  the  same  time  more  of  the  watery  parts 
of  the  blood  leave  the  capillaries.  This  makes  a  sivelling, 
while  the  pressure  of  the  swelling  upon  the  nerves  gives 


Beginning  of  inflammation  (x  400). 

a  white  blood  cells  adhering  to  the  wall  of  a 
capillary  and  passing  through  it. 

b  white  blood  cells  which  have  passed  out- 
side of  the  capillary  in  order  to  repair  an 
injury. 

c  white  blood  cells  passing  through  the  capil- 
lary. 

d  wall  of  capillary. 


BLEEDING,    WOUNDS,    AND   DISEASE   GERMS  75 

pain.    The  three  signs,  namely,  redness,  swelling,  and  pain, 
generally  mean  that  a  part  is  inflamed. 

138.  Repair  of  wounds.  —  The  object  of  the  increased 
quantity  and  action  of  the  blood  is  to  heal  the  injured  part. 
If  some  of  the  cells  of  a  part  have  been  killed  by  an  injury, 
the  white  blood  cells  eat  up  the  dead  parts  and  carry  them 
off  with  the  lymph.    Some  of  the  white  blood  cells  become 
branched,  and  fit  themselves  into  the  spaces  between  the 
cells,  and  so  become  a  part  of  the  flesh.     Thus  the  cut  or 
injured  parts  are  mended.     The  new  flesh  does  not  look 
like  the  old,  but  is  puckered  and  firmer.     It  is  called  a 
scar. 

139.  Taking  cold.  — Now   suppose   bacteria   are   doing 
damage  to  the  body,  or  get  into  the  lymph  spaces  after  it 
is  done.     Then  they  multiply  and  produce  poisons  which 
harm  the  body  far  more  than  the  first  injury.     The  white 
blood  cells  fight   these  bacteria.      Whole  armies  of  cells 
rush  to  the  spot  and  usually  soon  overcome  the  germs. 
But  many  times  the  white  blood  cells  are  killed  in   the 
fight.      Then  others  rush  in,  until  they  pack  the  lymph 
spaces  tightly  and  fill  the  ends  of  the  blood  tubes  and  so 
cut  off  the  supply  of  food.     So  the  bacteria  are  besieged 
until  they  are  starved  to  death,  but  the  cells  of  the  body 
also  starve.     Finally  the  germs,  the  white  blood  cells,  and 
the  cells  of  the  body  all  die  and  soften  and  run  out  as 
matter,  or  pus.      This  is  called  a  gathering,  or  abscess.     A 
boil  is  an  example  of  this.  '  After  the  matter  has  run  out, 
the  white  cells  grow  over  the  bottom  and  sides  of  the  hole 
and  soon  mend  it  with  a  scar.    So  a  few  of  the  cells  of  the 
body  give  their  lives  in  order  that  the  rest  may  be  saved. 
Those  that  were  killed  and  formed  the  foul  matter  were 
just  as  good  and  strong  cells  as  those  that  were  left  and 
healed  the  wound.    They  were  not  impurities  in  the  blood, 


76  APPLIED   PHYSIOLOGY 

but  were  its  strongest  and  purest  cells  which  went  out  to 
fight  enemies  and  were  killed.  After  they  die,  they  decay 
and  become  poisons,  and  so  must  be  thrown  off. 

The  same  thing  happens  in  a  cut.  The  bacteria  grow 
upon  its  surface,  while  the  white  blood  cells  fight  them 
until  they  are  killed  and  flow  away  as  matter.  If  the  cut 


a 


An  abceds  ( x  50) . 

a  epithelium  of  the  skin,  softened  and  bursting. 

b  white  blood  cells  which  have  packed  the  tissues  full  and  shut  out  nourishment. 

c  blood  tube  stopped  by  white  blood  cells. 

is  kept  closed  and  clean  so  that  the  germs  cannot  get  in, 
there  will  be  no  cold  in  the  cut,  but  the  white  blood  cells 
will  devote  all  their  energies  to  mending  the  cut.  Then 
the  cut  will  heal  in  a  few  days,  without  pain  or  much 
inflammation. 

When  you  sit  in  a  cold  wind  after  being  heated  by  exer- 
cise, the  tender  cells  of  your  nose  and  mouth  are  hurt,  and 
you  have  a  sore  throat.  Perhaps  some  bacteria  grow  there 
too.  Then  white  blood  cells  and  liquid  parts  of  the  blood 
pass  out  of  the  capillaries  and  form  the  thick  matter  which 
we  spit  out.  This  does  not  consist  of  impurities  of  the 


BLEEDING,    WOUNDS,   AND   DISEASE  GERMS  77 

blood,  but  it  is  what  your  body  is  using  to  mend  the  hurt 
and  to  destroy  the  bacteria.  We  insult  these  little  cells 
when  we  call  them  impurities,  while  they  are  keeping  off 
enemies  and  yet  mending  the  wound  too. 

140.  The  skin  in  healing.  —  While  the  white  blood  cells 
are  growing  and  healing  a  cut,  the  cells  upon  the  surface 
of  the  skin  around  the  edge  of  the  sore  slowly  spread  over 
it.     This  forms  a  new  skin  and  ends  the  healing.     This 
new  growth  of  skin  is  necessary  in  every  healing  process. 
When  the  new  flesh  grows  faster  than  the  skin,  the  skin 
cannot  keep  up  with  it,  and  so  the  flesh  forms  a  soft  red 
tuft  above  the  skin.     This  is  called  proud  flesh,  and  must 
be  burned  or  scraped  off  before  the  skin  can  finish  healing 
the  cut. 

141.  How  to  care  for  a  cut.  —  Bacteria  are  everywhere, 
and  readily  enter  a  cut  unless  they  are  kept  out.     The 
surgeon  keeps  them  out  by  wrapping  wounds  in  cloths 
which  have  been  boiled  or  steamed  in  order  to  kill  the 
germs.     He  also  puts  on  for  the  same  purpose  such  things 
as  carbolic  acid.     In  this  way  he  can  keep  the  germs  from 
the  wounds  which  he  makes,  and  so  the  white  blood  cells 
will  have  nothing  to  do  except  to  mend  the  wound.     Then 
in  a  few  days  even  the  largest  cut  grows  together  and  is 
whole  again. 

When  you  cut  yourself,  the  wound  will  soon  heal  if  you 
bind  it  up  with  a  clean  cloth  and  change  this  often  enough 
to  keep  the  wound  dry.  Then  no  germs  will  grow  in  the 
cut,  and  nothing  will  prevent  it  from  healing.  It  will  be 
still  better  to  put  on  the  dressings  something  which  will 
kill  the  disease  germs.  One  part  of  carbolic  acid  in  fifty 
of  water  is  good.  Friars'  balsam  is  good,  too.  Do  not 
put  on  a  sticky  salve,  for  it  keeps  in  the  disease  germs  and 
matter. 


78  APPLIED   PHYSIOLOGY 

142.  Catching  diseases.  —  Some  diseases,  like  measles, 
smallpox,  and  typhoid  fever  are  caught  from  other  cases 
of  the  same  disease.     These  diseases  are  caused  by  some 
germ  which  can  live  in  the  air  or  soil  after  it  passes  off 
from  the  sick  person.     One  may  get  these  diseases  by 
breathing  the  air  of  a  sick  room,  or  by  eating  some  of  the 
germs  which  stick  to  the  hands  or  clothes,  or  by  drinking 
some  well  water  into  which  slops  from  the  house  have 
trickled.     So  great  care  must  always  be  taken  of  a  person 
sick  with  a  catching  disease. 

In  the  first  place,  a  sick  room  needs  plenty  of  air,  even 
in  cold  weather.  This  drives  out  the  disease  germs  as  fast 
as  they  form.  Sunlight  also  kills  the  germs.  So  it  is 
almost  impossible  to  catch  a  disease  in  the  open  air. 

In  the  second  place,  the  sick  room  must  be  kept  clean. 
The  bedclothes  must  be  changed  often  and  washed,  and 
the  person  himself  must  be  bathed  often.  This  also 
removes  disease  germs. 

In  the  third  place,  soiled  clothing  must  be  boiled  to  kill 
the  germs,  or  else  they  will  carry  the  disease.  Slops  must 
be  buried,  or  else  have  carbolic  acid  or  some  such  sub- 
stance poured  over  them  to  kill  the  disease  germs. 

In  the  fourth  place,  you  must  avoid  handling  the  patient 
or  his  dirty  clothes.  When  you  come  from  the  sick  room 
you  must  not  eat  without  washing  your  hands.  You  must 
not  put  your  hands  or  fingers  to  your  mouth  in  the  sick 
room. 

143.  Effects  of  alcohol.  —  Since  alcohol  starves  and  poi- 
sons the  cells,  the  white  blood  cells  suffer  with  the  rest, 
and  are  not  able  to  fight  bacteria  or  to  repair  injuries  as 
they  should.    So  inflammation  is  more  likely  to  take  place. 
A  drinker  is  more  likely  to  get  pneumonia  or  consumption 
or  other  disease  of  the  lungs.     Alcohol  scalds  the  throat, 


BLEEDING,   WOUNDS,   AND   DISEASE   GERMS  79 

and  makes  it  tender  and  more  likely  to  take  cold.  Thus 
the  voice  of  the  drinker  is  often  so  hoarse  that  he  is  unable 
to  sing  or  talk.  Far  from  protecting  against  disease  or 
taking  cold,  alcohol  causes  a  person  to  be  more  liable  to 
sickness. 

SUMMARY 

1.  You  can  stop  any  bleeding  by  grasping  the  part  and 

making  firm  pressure. 

2.  When  a  part  of  the  body  is  injured,  it  soon  repairs 

itself. 

3.  Disease  germs,  called  bacteria,  can  grow  in  the  body. 

A  pin  prick  may  carry  thousands  of  them  inside  the 
body. 

4.  Bacteria  grow  in  the  lymph,  and  produce  such  diseases 

as  erysipelas  and  typhoid  fever. 

5.  When  a  part  of  the  body  is  hurt,  the  white  blood  cells 

rush  to  the  spot  and  grow  in  place  of  the  dead  cells, 
and  so  heal  the  wound. 

6.  When .  germs  of  disease  grow  in  the  body,  the  white 

blood  cells  attack  them.  Matter  which  runs  from  a 
wound  is  made  up  of  the  cells  which  the  disease 
germs  have  killed. 

7.  Taking  cold  means  that  bacteria  are  growing  in  some 

part  of  the  body. 

8.  Cleanliness,  to  keep  out  bacteria,  is  the  main  thing  in 

treating  a  cut. 

9.  Cleanliness,  fresh  air,  and  sunshine  are  the  main  things 
4          in  caring  for  a  sick  room. 


CHAPTER   IX 


RESPIRATION 

144.  Use  of  the  breath.  —  The  body  is  an  engine,  and  its 
power  is  made  by  burning  or  oxidation.  Every  cell  in  the 
body  must  breathe  in  oxygen  from  the  air,  but  only  a  few 
on  the  surface  have  access  to  it.  So  a  few  cells  are  set 
apart  for  the  work  of  carrying  it  to  the  rest.  Air  is  always 
going  in  and  out  of  the  nose  or  mouth.  When  we  stop 
breathing  for  only  a  few  seconds,  we  feel  short  of  breath, 
and  if  we  should  stop  for  a  few  min- 
utes, we  should  die.  Air,  then,  is  the 
most  needful  thing  which  we  take  into 
our  bodies. 

145.  The  air  passages  and  the  lungs. 
—  The  nose  opens  into  the  pharynx, 
which  is  just  back  of  the  mouth.  From 
the  pharynx  there  is  an  opening  into 
the  windpipe.  The  windpipe  is  a  tube 
about  six  inches  long.  It  branches 
into  two  tubes  called  bronchi,  one  for 
each  side  of  the  body.  Each  bronchus 
divides  like  the  branches  of  a  tree.  At 
the  ends  of  the  smallest  twigs  are  tiny 
bags  or  sacs,  with  very  thin  sides.  The  sacs  can  be 
blown  up  with  air.  The  bronchi  and  air  sacs  make  up 
the  lungs.  The  lungs  are  light  red  flesh,  much  like  a 
sponge.  The  air  in  them  crackles  when  they  are  squeezed. 

80 


A  frog's  lung  (X4). 


RESPIRATION 


8l 


Look  at  the  lungs  of  a  pig  or  calf  in  the  butcher's  shop, 
for  they  are  like  a  man's  lung.  A  frog's  lung  is  a  thin 
bag,  about  half  an  inch  in  diameter.  Upon  its  sides  are 
shallow  cups  like  the 
pockets  of  a  honey- 
comb. Each  air  sac  of 
a  man's  lung  is  like  a 
very  small  frog's  lung. 

146.  Breathing.  — 
The  lungs  are  hung  in 
a  box   called   the   chest 
or    thorax.      The    sides 
of    the    chest    are    the 
ribs,  and  its   bottom   is 
a  leaf  of  muscle  called 
the    diaphragm,    which 
stretches    like   an    arch 
across  the  inside  of  the 
body.      (See   page    22.) 
The  ribs  and  diaphragm 
can  be  moved  so  as  to 
make  the  chest  larger  or 
smaller.      When    it   be- 
comes    larger,    the    air 
is  sucked  into  the  lungs 
and  makes  them  larger. 

This  is  called  inspiration.  When  the  chest  is  made 
smaller,  air  is  driven  out  of  the  lungs.  This  is  called 
expiration.  This  takes  place  about  eighteen  times  a 
minute,  but  when  you  run  or  work  hard  you  must  breathe 
more  often. 

147.  Cilia.  —  The  lining  of  the  windpipe  and  bronchi  is 
made  of  cells  whose  inner  ends  are  covered  with  tiny  hairs 

ov.  PHYSIOL.  (INTER.)  —  6 


The  air  tubes  and  lungs. 

a  larynx  or  voice  box. 

b  trachea  or  windpipe. 

c  bronchi. 

d  air  sacs,  each  like  a  tiny  frog's  lung. 


82 


APPLIED    PHYSIOLOGY 


always  in  motion.  The  hairs  vibrate  in  such  a  way  as  to 
drive  anything  out  of  the  air  passages.  In  the  finest 
bronchi  they  reach  a  considerable  way  across  the  tube  and 
entangle  any  dust  which  may  reach  them.  So  they  pro- 
tect the  delicate  air  sacs  from  dust.  They  also  force 
mucus  towards  the  mouth,  so  that  we  can  get  rid  of  it 


a 


A  slice  from  the  trachea  (X  200). 

a  cartilage.  b  glands  in  the  mucous  membrane. 

c  lining  of  epithelial  cells. 

d  cilia  upon  the  surface  of  the  epithelium. 

when  we  have  a  cold.  Finally,  the  cilia  make  air  currents 
in  the  tiny  air  tubes,  and  so  hasten  the  exchange  of  pure 
for  impure  air. 

148.  Breathing  sounds.  —  As  air  goes  in  and  out  of  the 
lungs,  it  makes  a  low,  blowing  sound.  Listen  to  each 
other's  chests  while  breathing  deeply  and  notice  these 
sounds  of  breathing.  Listen,  also,  while  a  person  counts 
three.  You  will  feel  the  chest  tremble  and  hear  the  voice 
through  the  chest.  The  physician  listens  to  the  chest 
when  he  thinks  a  person  has  lung  disease.  By  the 


RESPIRATION 


Capillaries  upon  the  sides  of  an  air  sac 
(X  200). 


changes  in  the  sounds  he  can  tell  what  is  the  matter  with 
the  lungs. 

149.  What  air  does  to  the  blood.  —The  air  is  four  fifths 
nitrogen  and  one  fifth  oxygen  gas.     Both  gases  go  into  the 
air  sacs  of  the  lungs,  but 

all    the    nitrogen    comes 

back,  while  some  of  the 

oxygen  is  left  behind,  and 

some   carbonic   acid    gas 

and  water  are  put  in  its 

place.    We  must  see  what 

becomes  of   the   oxygen. 

Upon  the  sides  of  the  air 

sacs  is  a  close  network  of 

capillary     blood      tubes. 

Their  sides  are  very  thin. 

While  they  keep  the  blood 

from  running  out,  they  let  oxygen  gas  pass  through  very 

easily.     The  red  blood  cells  are  oxygen  carriers,  and  as 

they  shoot  through  the  capillaries  they  take  tiny  loads  of 

oxygen  and  carry  it  to 

aU   parts   of    the   body 

for  the  use  of  the  cells. 

Each    load    of    oxygen 

causes  its  red  blood  cell 

to  become  bright  red  in 

color,  and  so  the  whole 

blood  becomes  a  brighter 

red  as  it  passes  through 

the  lungs. 

150.  How  air  reaches  the  cells  of  the  body.  —  From  the 
lungs  the  blood  goes  to  the  left  side  of  the  heart  and  is 
sent   through    the   capillaries   to   all   parts   of    the   body. 


Diagram  of  the  respiration  of  cells. 


84  APPLIED    PHYSIOLOGY 

Not  even  oxygen  can  pass  through  the  sides  of  the  arte- 
ries, but  when  it  reaches  the  capillaries  it  passes  out  very 
easily.  So  in  the  capillaries  it  leaves  the  red  blood  cells 
and  goes  to  the  cells  of  the  body.  When  oxygen  has  left  the 
blood  cells,  they  become  of  a  darker  color.  So  blood  in  the 
veins  is  always  of  a  darker  color  than  blood  in  the  arteries. 

151.  Oxidation  in  the  cells.  —  The  oxygen  which  goes  to 
the  cells  of  the  body  burns,  or  oxidizes,  their  albumin,  fat, 
and  sugar,  producing  carbonic  acid  gas  and  water.     All 
oxidation  inside  the   body  takes    place    in   a  living   cell. 
Oxidation  is  the  real  act  of  breathing.     The  cells  of  the 
body  are  always  getting  oxygen  and  giving  out  carbonic 
acid  gas  and  water.     The  water  drains  off  by  the  lymph. 
The  carbonic  acid  gas  goes  through  the  sides  of  the  capil- 
laries and  so  back  to  the  blood,  where  it  is  dissolved  and 
carried  to  the  lungs.     So  blood  in  the  veins  has  less  oxygen 
and  more  carbonic  acid  gas  than  blood  in  the  arteries.     It 
is  the  lack  of  oxygen,  not  the  presence  of  carbonic  acid  gas, 
that  makes  the  venous  blood  dark  in  color. 

152.  How  carbonic  acid  gas  leaves  the  body.  —  All  the 
venous  blood  flows  into  the  right  side  of  the  heart  and  is 
pumped  to  the  lungs.     In  the  lungs  the  carbonic  acid  gas 
leaves  the  blood  and  passes  off  through  the  sides  of  the 
capillaries  into  the  air  sacs.     It  is  then  breathed  out  by  the 
next  breath.     At  the  same  time,  oxygen  passes  to  the  red 
blood  cells  again,  and  the  blood  is  ready  for  another  round 
of  the  body.     So  the  blood  carries  oxygen  to  the  cells  of 
the  body  and  gets  carbonic  acid  gas  from  them,  and  then 
goes  to  the  lungs  to  give  up  the  carbonic  acid  gas  in 
exchange  for  oxygen  from  the  air.     The  real  breathing  in 
the  body  is  done  in  the  capillaries  and  cells.     The  lungs 
are  places  where  the  red  blood  cells  get  oxygen  to  carry  to 
the  cells. 


RESPIRATION  8$ 

153.  How  rapidly  oxygen  is  used.  — When  the  draft  of 
a  stove  is  closed,  the  fire  stops  burning  at  once.     Just  so 
the  oxidation  in  the  body  stops  when  we  stop  breathing. 
In  a  lung  full  of  air  there  is  enough  oxygen  to  last  from 
one  half  to  one  minute.     After  that  we  feel  very  short  of 
breath  and  cannot  keep  ourselves  from  breathing.     A  frog 
can  take  a  big  mouthful  of  air  which  will  last  him  some 
time  while  he  is  under  water,  but  finally  he  must  come  to 
the  top  for  more  air.     A  man  cannot  store  air  in  his  body, 
and  so  must  keep  taking  in  air  every  moment.     The  oxy- 
gen goes  quickly  to  the  cells,  and  starts  the  oxidation  at 
once.     A  few  deep  breaths  will  relieve  almost  any  short- 
ness of  breath. 

154.  Why  we  get  short  of  breath.  —  When  we  run  or 
work  hard,  our  cells  use  a  great  deal  of  oxygen.     Then 
we  breathe  deeper  and  take  in  more  oxygen.     But  after 
a  while  the  red  blood  cells  have  all  they  can  carry.     Then 
we  cannot  get  more,  but  feel  very  short  of  breath.     So  we 
stop  work  until  we  have  sufficient  oxygen  again.    By  train- 
ing, we  can  educate  the  heart  and  lungs  so  that  more 
oxygen  may  be  carried.     Then  we  can  run  a  long  distance 
without  getting  out  of  breath. 

155.  Mouth    breathing.  —  You    should    always   breathe 
through  the  nose.     This  warms  the  air  and  strains  out  its 
dust.     When  you  breathe  through  the  mouth,  the  cold  air 
and  dust  make  you  cough  and  are  very  likely  to  give  you 
a  cold. 

Some  children  have  masses  of  flesh  growing  either  in 
the  throat,  pharynx,  or  the  nose.  Such  children  always 
keep  their  mouths  open,  for  they  cannot  breathe  through 
the  nose.  The  upper  lip  seems  too  short  for  their  teeth. 
The  jaw  is  narrow  and  the  teeth  point  forward.  This 
deforms  the  face  for  life.  If  these  masses  are  removed 


86  APPLIED   PHYSIOLOGY 

early,  as  can  be  easily  and  painlessly  done,  the  jaw  will 
grow  into  proper  shape,  and  allow  the  child  to  breathe 
through  its  nose  and  become  well  again. 

Many  children  breathe  through  the  mouth  from  habit. 
They  should  keep  from  it  even  when  they  feel  short  of 
breath. 

Another  reason  why  a  child  should  not  breathe  through 
the  mouth  is  that  it  may  produce  earache. 

156.  Deep  breathing.  —  The  larger  your  lungs  are,  the 
more  air  you  can  take  in.     So  you  ought  to  take  a  deep 
breath  several  times  a  day.     Then  hold  your  breath  as  long 
as  possible.     In  this  way  you  will  increase  the  size  of  your 
lungs  and  become  able  to  run  a  long  distance.     It  will  also 
make  you  stronger  all  over,   and  be  a  great   protection 
against  your  taking  diseases. 

A  man  should  be  able  to  make  his  chest  two  inches 
larger  around  with  each  breath.  Three  or  four  inches 
will  be  better.  The  more  you  can  expand  your  lungs,  the 
longer-winded  you  will  be. 

157.  Position  of  the  body.  —  You  should  always  keep 
your  shoulders  thrown  back  and  your  chest  forward,  so  as 
to  give  the  lungs  all  the  room  you  can.    A  round-shouldered, 
flat-chested  man  has  little  room  for  his  lungs. 

158.  Tight    clothing.  —  When    your    clothes    are    tight 
around  the  body,  you  cannot  expand  your  lungs  so  much 
as  you  wish,  and  so  you  cannot  run  or  work  without  getting 
out  of  breath.     If  you  wear  tight  clothes  day  after  day, 
your  lungs  will  finally  grow  small  and  you  will  never  be 
strong. 

The  waist  should  be  large  around  so  as  to  give  room  for 
the  liver  as  well  as  the  lungs.  Girls  need  as  much  room 
for  their  livers  and  lungs  as  boys.  They  do  a  great  deal 
of  harm  to  themselves  by  making  their  waists  small. 


RESPIRATION 


Diagram  of  artificial  respiration,  showing  inspiration. 

The  arrows  show  that  the  arms  are  moved  outward 
from  the  sides  of  the  chest. 


159.   Artificial    respiration.  —  We    can    breathe    as    we 

choose  for  a  few  moments,  but  nature  finally  makes  us 

breathe    as    we 

should.      Some- 
times  a    person 

is      injured     in 

such  a  way  that 

he        cannot 

breathe.      In 

drowning  or  an 

electric  shock  a 

person     stops 

breathing.        If 

he  can  only  be  made  to  breathe  again,  his  life  will  be 

saved.     Every  one  should  know  how  to  make  a   person 

breathe. 

When  any  one  presses  your  chest  or  stomach,  it  drives 

the  air  out  of  your  nose  and  makes  a  sound.     In  the  same 

way  you  can 
make  air  pass  in 
and  out  of  a  life- 
less  body  by 
pressing  upon  the 
ribs.  If  you  press 
as  often  as  you 
yourself  breathe, 
the  body  will  get 


Diagram  of  artificial  respiration,  showing  expiration. 

The  arrows  show  that  the  arms  are  carried  directly  for- 
ward until  they  are  pressed  hard  against  the  chest. 


a  large  quantity 
of  air.  So  if  a 
person  seems  dead  from  drowning  or  electric  shock,  try  to 
perform  his  breathing  for  him.  You  can  do  no  harm  and 
you  may  save  his  life. 

160.  How  to  make  a  lifeless  person  breathe.  —  Here  is  a 


88 


APPLIED    PHYSIOLOGY 


good  way  to  perform  artificial  respiration :  Lay  the  person 
upon  his  back.  Kneel  down  at  his  head  and  grasp  his 
arms  at  his  elbows.  Now  sweep  them  out  from  his  body 
and  bring  them  nearly  together  above  his  head.  This 
expands  the  chest  and  draws  air  into  the  lungs. 

Next,  sweep  the  arms  downwards  and  press  them  hard 
against  his  chest.  This  will  force  the  air  out  of  the  lungs 
and  will  probably  make  a  sound.  Keep  this  up  about  as 
often  as  you  breathe.  You  may  need  to  keep  doing  it  for 
an  hour  or  two  before  a  person  revives. 

161.  Drowning.  —  In  cases  of  drowning,  the  lungs  will 
contain  some  water.  Then  you  should  turn  the  person 
upon  his  face  and  lift  him  by  his  chest  so  as  to  allow  the 
water  to  drain  out.  Do  this  for  a  few  seconds,  and  then 
keep  on  with  the  artificial  respira- 
tion. Do  not  get  hurried  or  excited. 
Remember  that  the  life  of  the  per- 
son may  depend  upon  your  causing 
slow  and  continuous  breathing.  Do 
not  wait  for  help,  but  begin  at  once. 
162.  The  voice.  —  By  means  of 
the  breath  we  talk,  and  laugh,  and 
cry,  and  sing,  and  make  all  kinds 
of  sounds  to  express  our  thoughts 
and  feelings.  Nearly  all  of  these 
sounds  are  made  in  a  little  box  called 
the  larynx,  in  which  the  windpipe 
begins.  Its  outside  can  be  felt  in 
the  upper  part  of  the  neck,  under 
the  chin,  where  it  forms  the 
Across  the  middle  of  the  box  two  bands 
are  stretched.  These  bands  are  called  vocal  cords.  They 
slide  sidewise  and  can  be  made  either  tight  or  loose. 


—  a 


Back  view  of  the  larynx. 

a  thyroid  cartilage. 
b  vocal  cords. 
£  movable 

attachment  of 

cords. 

d  cricoid  cartilage. 
e  epiglottis. 


Adams  Apple. 


RESPIRATION 


89 


When  they  are  tightened  and  brought  near  together,  and 
a  breath  of  air  is  driven  out  through  them,  a  noise  is  made. 
The  sound  varies  with  the  tightness  and  the  nearness  to- 
gether of  the  cords,  and  the  force  with  which  air  is  driven 
out.  It  is  further  changed  by  the  mouth  and  nose,  which 
act  as  a  sounding  box.  In  talking,  the  tongue  and  lips  are 
moved  so  as  to  make  different  kinds  of  sounds.  These 
sounds  are  so  very  much  alike  that  the  sounds  of  a  for- 
eigner's language  seem  the  same,  no  matter  what  he  is 
saying.  Yet  we  learn  to  make  the  sounds  with  great  ex- 
actness and  rapidity,  and  to  tell  their  difference  easily. 


Top  view  of  the  larynx,  with  the 
vocal  cords  closed,  as  in  speaking. 

a  epiglottis.        b  vocal  cords. 


Top  view  of  the  larynx,  with  the 
vocal  cords  open,  as  in  breathing. 

a  epiglottis.        b  vocal  cords. 


163.  Care  of  the  voice.  —  The  larynx  becomes  tired,  like 
any  other  part  of  the  body.     So  it  is  harmful  to  strain  the 
voice  by  loud  shouting  or  singing.     Breathing  through  the 
mouth  is  also  harmful,  especially  if  the  air  be  cold  or 
damp.     Using  the  voice  while  the  throat  is  sore  is   also 
harmful.     Singing  notes  of  very  high  pitch  is  also  very 
tiresome  to  the  voice. 

It  is  easy  to  form  the  habit  of  talking  in  loud,  coarse 
tones.  Now  the  tones  of  the  voice  express  our  feelings. 
We  ought  to  be  careful  always  to  speak  in  pleasant  tones 
so  as  to  make  others  feel  happy  even  if  we  are  not  happy. 
Then  we  ourselves  shall  be  more  likely  to  be  happy. 

164.  Alcohol  and  oxidation.  —  We  have  already  studied 


90  APPLIED  PHYSIOLOGY 

the  process  by  which  alcohol  is  carried  to  the  liver,  and 
there  takes  the  oxygen  which  should  go  to  oxidize  the 
albumin,  fat,  and  sugar  of  the  body  (see  §  100).  So  when 
alcohol  is  used,  not  only  the  liver,  but  also  all  other  cells  of 
the  body  lack  oxygen,  and  cannot  work  as  they  should. 
It  should  be  remembered  that  alcohol  is  oxidized  in  the 
liver,  and  that  none  reaches  the  other  cells  of  the  body. 
Two  or  three  drinks  of  whisky  use  as  much  oxygen  as 
the  whole  body  uses  in  an  hour.  So  the  cells  of  the  body 
cannot  breathe  properly  when  strong  drink  is  used. 

165.  Alcoholic  breath.  —  When   alcohol    is    swallowed, 
some  remains  in  the  throat  and  gives  a  bad  odor  to  the 
breath.     But   it  also    hinders   digestion    and   produces   a 
coated  tongue  and  biliousness.     This  gives  a  still  worse 
odor  to  the  breath.     Alcohol  itself  does  not  go  off  by  the 
breath,  for  it  is  oxidized  in  the  liver. 

166.  Tobacco  and  the  lungs.  —  The  nicotine  of  tobacco 
has  a  sharp,  peppery  taste,  and  makes  the  throat  tender 
and  the  voice  hoarse.     It  hurts  the  nerves,  so  that  there  is 
a  feeling  as  though  something  were  stuck  in  the  throat. 
Trying  to  cough  it  out  strains  the  throat.     By  keeping  the 
throat  tender  in   this  way  a  person  makes  himself  more 
liable  to  take  cold.     Tobacco  smoke  in  the  windpipe  and 
bronchi  is  still  more  harmful,  for  these  parts  are  more  ten- 
der than  the  throat.     Instead,  then,  of  making  a  singer's 
voice  clear  and  strong,  it  makes  it  hoarse  and  weak. 

Tobacco  smoke  has  the  same  poisons  as  tobacco  itself, 
besides  other  poisons  developed  by  the  burning.  All  these 
poisons  in  the  smoke  can  enter  the  body.  Cigarette  smoke 
is  drawn  deeply  into  the  lungs.  Consequently  it  is  more 
likely  to  remain  in  the  body  and  poison  the  smoker.  Of  all 
forms  of  smoking,  cigarette  smoking  is  the  most  harmful. 
Yet  many  boys  suppose  it  to  be  the  least  harmful  form. 


RESPIRATION  91 

167.  Adulterated  tobacco.  —  Some  cigars,  cigarettes,  and 
chewing  tobacco  have  substances  added  to  improve  their 
taste.  For  this  purpose,  molasses,  licorice,  vanilla,  and 
the  like,  are  added.  Some  of  these  things  do  harm,  and, 
in  any  case,  the  addition  of  such  substances  is  a  fraud. 

SUMMARY 

1.  The  lungs  are  made  of  tiny  sacs,  upon  whose  side& 

capillaries  are  spread. 

2.  By  moving  the  chest  walls,  air  is  drawn  into  the  lungs 

and  forced  out  again. 

3.  As  the  red  blood  cells  shoot  through  the  capillaries  of 

the  lungs,  they  take  up  tiny  loads  of  oxygen  from 
the  air.  This  makes  the  blood  bright  red  in  color. 

4.  The  blood  carries  oxygen  to  the  capillaries  of  the  body. 

There  the  oxygen  goes  to  the  cells  of  the  body. 

5.  The  oxygen  oxidizes  the  cells  to  carbonic  acid  gas  and 

water.     Thus  the  cells  breathe. 

6.  The  blood  carries  the  carbonic  acid  gas  to  the  lungs, 

and  gives  it  out  to  the  air. 

7.  When  the  cells  have  used  all  the  air  in  the  blood,  we 

feel  short  of  breath. 

8.  We  should  breathe  deeply  and  through  the  nose.    We 

should  sit  and  stand  straight,  and  wear  loose  clothes, 
to  give  our  lungs  room. 

9.  In  a  case  of  drowning,  you  can  make  air  enter  and 

leave  the  lungs  by  pulling  the  arms  above  the  head 
and  then  pressing  them  against  the  chest.  Do  this 
as  often  as  you  yourself  breathe. 

10.  Air  passing  between  two  cords  in  the  larynx  makes 

the  sound  of  the  voice. 

11.  Alcohol  takes  oxygen  from  the  cells  of  the  body. 

12.  Tobacco  smoke  irritates  and  poisons  the  lungs. 


CHAPTER   X 

VENTILATION,   HEAT,    AND   CLOTHING 

168.  Need  of  fresh  air.  —  Since  oxygen  is  taken  from 
the  air  and  carbonic  acid  gas  goes  out  in  its  place,  the 
air  in  a  short   time   becomes    unfit   for  use   unless  it  is 
changed.     Carbonic  acid  gas  is  but  slightly  poisonous  in 
itself,   or  else  the  body  would  always  be  poisoned,   but 
when    it   is  breathed   into    the  air   the   same    amount   of 
oxygen  has  been  taken  away  from  the  air.     Only  a  little 
oxygen  can  be  taken  away  from  the  air  before  the  body 
feels  the  loss.     In  a  church,  the  windows  are  sometimes 
closed  tightly  and  but  little  new  oxygen  can  get  in  to  take 
the   place   of    that  which    is   breathed.     So   there    is  not 
enough  oxygen  to  keep  up  the  full  oxidation  within  our 
bodies.      As   a   result,  their   power  is  lessened,   and  we 
become  so  sleepy  that  the  best  sermon  does  not  keep  us 
awake. 

169.  Foul  air.  —  Water  is  always  evaporating  from  ihe 
nose  and  mouth  and  going  out  by  the  breath.    Odors  from 
the  mouth  and  clothes  also  enter  the  air.     The  moisture 
and  odors  are  very  unpleasant  to  sensitive  persons  and 
may  of  themselves  cause  sickness.     Disease  germs,  such 
as  those  of  measles  and  smallpox,  are  often  given  off  by 
unclean  persons.     They  are  no  more  poisonous  in  a  close 
room  than  out  of  doors,  but  in  a  room  they  are  not  scat- 
tered by  the  wind,  and  so  another  person  is  far  more  likely 
to  breathe  them  in  than  he  would  be  in  the  open  air.     So  a 

92 


VENTILATION,   HEAT,   AND   CLOTHING 


93 


change  of  air  is  very  necessary  where  people  are  together 
in  a  tight  room. 

170.  Ventilation.  —  Changing  the  air  of  a  room  is  called 
ventilation.  In  large  buildings  it  is  often  done  by  fans 
and  pumps,  but  in  most  buildings  it  is  done  by  natural 


Diagram  of  the  natural  ventilation  of  a  room. 
The  arrows  indicate  the  direction  of  the  air  currents. 

currents  of  air.  Breathed  air  is  warmed  in  the  lungs. 
Warm  air  is  lighter  than  cold  air  and  so  rises  to  the  ceil- 
ing. If  the  upper  part  of  the  window  is  opened,  the 
warmed  air  will  pass  out  while  the  fresh  air  will  enter  by 
cracks  in  the  doors  and  lower  parts  of  the  windows.  On 
a  cold  day  the  difference  between  the  warmed  and  cold 
air  is  very  great.  This  causes  a  strong  current ;  but  on 


94  APPLIED   PHYSIOLOGY 

a  hot  summer's  day  the  breathed  air  is  of  about  the  same 
warmth  as  the  air  outside ;  so  there  will  be  no  current 
unless  the  wind  blows.  This  makes  buildings  very  warm 
and  close  in  the  summer. 

171.  How  to  ventilate.  — When  only  one  or  two  people 
live  in  a  room,  the  ventilation  by  cracks  in  the  doors  and 
windows  is  enough  and  in  very  cold  weather  may  be  too 
much.     In  new  and  very  tightly  built  houses,  the  cracks 
are  few  and  small,  and  more  ventilation  will  be  needed. 

The  simplest  way  to  ventilate  a  room  is  to  raise  or  lower 
a  window.  But  then  the  cold  fresh  air  may  blow  on  some 
one's  head  and  cause  a  cold.  So  you  must  be  careful  to- 
open  a  window  through  which  the  wind  will  not  blow. 
Another  way  is  to  raise  the  lower  window  sash  and  fit  a. 
board  to  fill  the  opening.  Then  the  fresh  air  will  come  in 
between  the  two  sashes  and  will  make  less  of  a  draft. 

Some  houses  are  heated  by  hot-air  registers.  If  the  air 
in  the  register  is  pure,  this  will  ventilate  the  room.  Some- 
times an  opening  is  made  in  the  chimney  near  the  ceiling 
so  that  the  impure  air  can  get  out ;  then  more  pure  and 
warm  air  will  come  in.  In  large  buildings  like  schools  and 
theaters,  there  is  often  a  fan  run  by  machinery.  This 
forces  out  the  impure  air  and  fills  the  room  with  pure  air. 
So  the  air  can  be  changed  as  fast  as  we  wish. 

172.  Sick  rooms.  —  It  is  very  important  to  ventilate  a 
sick  room,  for  sick  persons  need  all  the  oxygen  they  can 
get.     They  should  not  be  disturbed  with  unpleasant  odors. 
Especially  in  some  kinds  of  sickness,  disease  germs  need 
to  be  carried  away  as  fast  as  they  are  given  off. 

173.  Bedrooms.  —  Night  air  is  exactly  the  same  as  air 
in  the  daytime,  except  that  it  is  cooler.     Sleeping  rooms- 
should  be  as  freely  opened  to  the  air  at  night  as  in  the 
daytime.     The  air  of  any  room  ought  to  be  changed  often 


VENTILATION,    HEAT,   AND    CLOTHING  95 

enough  to  prevent  any  odor  in  the  room,  for  air  that  has 
no  odor  is  generally  pure  and  safe  for  use. 

174.  Warmth  of  the  body.  —  Heat  is  produced  by  oxi- 
dation.    This  warms   the    whole   body  and   also    gives  it 
power  to  think,   and  move,  and  work.     Oxidation  takes 
place  in  every  cell  of  the  body,  but  most  of  the  fat  is 
oxidized  in  the  cells  of  the  lungs,  and  most  of  the  sugar 
in  the  cells  of  the  liver.      Muscle  cells  also   produce  a 
great  deal  of  heat  when  they  work.     The  body  has  the 
power  of  making  its  fires  burn  high  or  low  as  its  work 
needs,  but  its  own  warmth  always  remains  the  same.     A 
thermometer  shows  its  temperature  to  be  98.5  degrees  F., 
whether  we  feel  warm  or  cold. 

175.  The  feeling  of  heat  and  cold.  — We  sometimes  feel 
very  warm   and  again  very  cold,  but  our  bodies   always 
have  the  same  degree  of  heat.     We  feel  warmth  mostly 
in  the  skin.     So  if  the  skin  is  warm,  we  feel  warm  all 
over,  but  if  it  is  cold,  we  feel  chilly  all  over.     In  fevers  a 
sick  person  often  feels  very  cold,  for  his  skin  may  be  cold 
while  his  body  may  really  be  in  a  hot  fever. 

176.  How  the  body  varies  the  heat.  —  When  we  work 
hard,  we  need  a  great  deal  more  heat  than  when  we  are 
still.    In  winter  we  also  need  much  heat  to  warm  the  body, 
while  in  summer  we  need  but  little.     So  we  must  vary 
the  amount  of  heat.     We  can  do  this  by  varying  our  food. 
Fat  makes  a  great  deal  of  heat.     So  in  winter  we  like  fat 
meat.     In  summer  we  do  not  like  fat  so  well,  but  prefer 
fruit.     This  has  little  fat,  but  a  great  deal  of  sugar,  which 
produces  less  heat.     In  winter  we  eat  more  food  than  in 
summer.      When   we    move   about,  we   are  warmer  than 
when  we  keep  still.     So  in  winter  we  feel  like  working,  for 
we  need  the  heat  of  exercise  to  keep  ourselves  warm. 

177.  How  the  skin  gives  off  heat.  —  The   body   has   a 


96  APPLIED   PHYSIOLOGY 

temperature  of  98.5  degrees  F.  A  room  at  this  warmth 
would  seem  hot  to  us.  Even  80  degrees  F.  is  too  warm. 
70  degrees  F.  seems  about  right.  This  is  only  a  little  more 
than  half  way  between  freezing  and  the  warmth  of  our 
body.  So  heat  is  always  passing  off  from  the  skin  and 
warming  the  air.  We  get  rid  of  a  great  deal  of  heat  in 
this  way. 

On  a  cold  day  the  heat  goes  off  faster  than  on  a  warm 
day.  Then  we  should  expect  our  bodies  to  be  colder. 
But  nature  causes  the  blood  tubes  of  the  skin  to  become 
smaller  so  as  to  keep  some  of  the  blood  away  from  the 
skin.  Then  no  more  than  the  right  amount  of  heat  will 
pass  off,  and  we  shall  still  feel  warm. 

On  a  warm  day  the  heat  will  pass  off  from  the  skin 
more  slowly.  Then  the  blood  tubes  in  the  skin  become 
larger,  and  bring  more  blood  to  the  surface.  Thus  more 
heat  can  pass  off,  and  the  body  will  be  kept  at  the  right 
warmth. 

178.  How  the  perspiration  affects  our  warmth.  —  A  wet 
skin  always  feels  cold,  even  if  the  water  is  warm  when  it 
is  put  on  the  skin.  This  is  because  the  heat  passes  off  in 
the  steam  as  the  water  dries.  The  skin  is  always  moist 
with  sweat  or  perspiration.  We  cannot  see  it,  for  it  passes 
off  as  fast  as  it  comes  out.  But  as  it  dries,  it  takes  away 
a  great  deal  of  heat. 

On  cold  days  only  a  little  perspiration  is  poured  out,  for 
enough  heat  will  pass  off  without  it.  On  warm  days  a 
great  deal  will  often  be  produced,  so  that  it  may  not  dry 
so  fast  as  it  is  formed.  Then  it  collects  in  drops,  and 
even  runs  down  the  face. 

The  perspiration  enables  us  to  endure  great  heat.  Men 
have  staid  in  hot  ovens  for  some  time  without  injury,  for 
the  perspiration  carried  the  heat  away  from  their  bodies. 


VENTILATION,   HEAT,   AND   CLOTHING  97 

179.  Fever.  —  When  the  body  becomes  too  warm,  we 
are  in  a  fever,  and  are  sick.     If  the  temperature  of  the 
body  is  only  one  or  two  degrees  too  much,  we  do  not  feel 
well.     A  temperature  of  105  degrees  F.  is  a  high  fever,, 
and  is  dangerous  to  life. 

When  we  have  a  fever,  we  are  very  thirsty.  Then  we 
ought  to  drink  cold  water.  This  will  help  to  lower  the 
fever,  and  will  also  help  to  wash  away  the  poison  of  the 
disease.  It  is  also  a  good  plan  to  bathe  the  body  often 
for  the  sake  of  cooling  it.  Keep  the  room  cool,  and 
have  little  bed  covering,  for  the  sick  person  needs  to  be 
cooled,  and  he  is  in  little  danger  of  catching  cold. 

180.  Sunstroke.  —  When  exposed  to  a  great  heat  under 
a  hot  sun  or  in  a  hot  room,  the  body  sometimes  gets  too- 
warm.     Then  the  person  suddenly  feels  sick  and  faint. 
He  is  suffering  from  a  sunstroke.     This  is  a  dangerous 
condition.     It  is  most  likely  to  occur  on  hot,  damp  days. 
On  such  days  babies  are  very  apt  to  become  sick  from  the 
heat. 

In  sunstroke  the  person  should  be  carried  to  a  cool  spot. 
Put  cold  water  or  ice  to  his  head  and  body  so  as  to  cool 
him  as  soon  as  possible.  He  will  need  a  long  rest  after  he 
recovers. 

181.  Burns.  —  A  temperature  of  120  degrees  F.  is  all  the 
skin  can  endure.     Above  this  the  heat  produces  a  smart- 
ing pain,  and  injures  or  kills  the  skin.     If  the  heat  is  very 
great,  the  whole  thickness  of  the  skin  may  be  burned. 

When  a  person  is  burned,  put  cold  water  upon  the  burn  at 
once,  so  as  to  stop  the  pain.  Then  put  on  some  common 
baking  soda,  or  some  oil  of  any  kind.  A  mixture  of  lin- 
seed oil  and  limewater  is  always  good.  This  soothes  the 
pain,  and  keeps  the  parts  soft.  Healing  will  take  place 
slowly.  Use  the  oil  dressing  until  the  burn  has  healed, 
ov.  PHYSIOL.  (INTER.) — 7 


98  APPLIED   PHYSIOLOGY 

182.  Burning  clothing.  —  If  the  clothes  catch  fire,  they 
are  very  likely  to  burn  a  person  to  death.      The  great 
danger  is  that  the  fire  may  be  breathed  into  the  nose 
and  lungs.     So  a  person  whose  clothes  are  on  fire  should 
lie  down  at  once.     This  will  also  keep  the  flames  from 
spreading  over  his  whole  body.     If  he  now  roll  over  and 
over,  he  will  be  very  likely  to  smother  the  flames.     At 
any  rate,  they  will  spread  slowly,  and  will  not  reach  his 
face. 

If  you  see  a  person's  clothes  catch  fire,  at  once  throw 
him  to  the  floor  and  roll  him  about.  You  can  also  wrap 
your  coat  or  the  carpet  about  him,  and  thus  smother  the 
flames. 

183.  Effects  of  cold.  — When  a  person  is  exposed  to  very 
intense  cold  he  becomes  drowsy,  and  finally  falls  asleep. 
Then  he  is  near  death  unless  he  is  aroused.     So  when 
a  person  is  very  cold  you  must  not  let  him  rest,  but  keep 
him  moving  about. 

When  a  part  of  the  body,  as  a  hand  or  an  ear,  is  very 
cold,  it  becomes  numb  so  that  it  cannot  feel.  Then  we 
may  think  the  part  is  warm,  since  we  no  longer  feel  the 
cold.  But  soon  it  may  freeze. 

Freezing  is  very  apt  to  kill  the  part  frozen.  Rub  it  with 
snow,  or  place  it  in  ice  water  and  let  it  grow  warm  very 
gradually.  If  it  is  thawed  quickly,  it  will  surely  die,  but 
if  it  thaws  slowly,  it  may  finally  get  well,  but  it  will  be 
sore  and  will  smart  and  itch  for  a  long  time. 

184.  Catching   cold.  —  When  one  part  of   the  body  is 
colder  than  another,  the  blood  is  driven  from  the  cold  part 
and  collects  in  other  parts  of  the  body.     This  disturbance 
is  very  apt  to  injure  the  cells  and  make  us  take  cold.     For 
this  reason  damp  and  cold  feet  are  liable  to  cause  sickness. 
We  ought  to  wear  thick-soled  shoes  or  rubbers  on  every 


VENTILATION,   HEAT,:'A<NI>,  (JLCfTjEMNG - » ,  ;,   ,  ,    99 

wet  day.  We  ought  to  be  very  careful  how  we  cool  our 
bodies  when  we  are  very  warm.  We  are  liable  to  catch 
cold  if  we  go  from  a  warm  room  into  the  cold  air  without 
putting  on  extra  clothing. 

185.  Heating  houses.  —  In  cold  weather  we  cannot  keep 
warm  without  warming  the  air,  so  that  less  heat  will  pass 
off  from  the  body.     When  houses  were  heated  with  open 
fireplaces,  there  was  a  roaring  draft  up  the  chimney  with 
perfect  ventilation,  but   the   room  was   always   cold   only 
a  little  way  from  the  fire.     Now  we  use  stoves.     They  do 
not  use  much  air  and  so  do  not  give  much  ventilation. 
If  they  give  off  dust  and  gas,  they  may  make  the  air  bad. 

In  many  houses,  a  furnace  in  the  cellar  is  used  to  send 
heat  through  pipes  to  all  the  rooms.  This  gives  a  great 
deal  of  ventilation  and  is  a  good  way  of  heating.  Steam 
in  pipes  is  also  used  to  heat  houses.  This  heats  the  rooms 
well  but  does  not  afford  any  ventilation.  When  it  is  used 
we  must  be  careful  to  let  in  enough  fresh  air. 

Kerosene  stoves,  or  other  kinds  of  fire  in  which  the 
smoke  and  burned  products  do  not  pass  off  through  a 
chimney,  are  the  worst  ways  of  heating,  for  they  not  only 
use  the  air  but  they  also  pour  foul  gases  into  it. 

186.  The  proper  warmth  of  a  room.  —  The  best  tempera- 
ture for  a  house  is  about  70  degrees  F.     This  feels  neither 
too  warm  nor  too  cold.     For  a  bedroom  the  temperature 
should  be  60  degrees  F.  or  less. 

187.  Clothing.  —  Sometimes  nature  cannot  keep  us  warm 
enough  in  cold  weather,  or  protect  us  from  the  heat  of 
summer,   and   so  men  protect  themselves  with  clothing. 
In  cold  weather  our  object  is  to  keep  the  heat  from  pass- 
ing off  from  the  body,  and  we  wrap  ourselves  in  thick 
clothes.     Clothing  simply  keeps  in  the  heat  of  the  body 
without  adding  any  new  heat. 


IOQ  APPLIED   PHYSIOLOGY 

188.  Fur.  —  Fur   lets   the   least  heat  pass  off   and  so 
makes  the  best  winter  coat.     The  air  between  its  separate 
fibers  is  a  great  help  in  keeping  in  the  heat.     When  the 
fur  is  matted  down,  it  lets  more  heat  pass  out  and  is  not 
so  warm. 

189.  Woolen.  —  Next  to  fur  in  warmth  is  woolen  cloth- 
ing.    Soft  cloth  is  warmer  than  hard  or  stiff  cloth,  for  it 
holds  more  air.     Silk  is  even  better  than  wool  to  keep 
in  the  heat. 

190.  Cotton.  —  Cotton  lets  heat  pass  through  it  readily, 
and  so  is  cold  clothing.     Linen  lets  heat  pass  through  still 
more  easily,  and  is  still  colder;  but  if  enough  cotton  or 
linen  is  worn,  it  will  keep  in  the  heat,  and  so  keep  the 
body  warm  on  a  cold  day.     When  linen  or  cotton  under- 
clothing is  worn,  a  slight  draft  of  air  chills  the  body,  for 
the  underclothing  does  not  keep  in  the  heat,   and  so  a 
person  is  liable  to  take  cold. 

191.  How  to  clothe  the  body.  —  If  a  person  wears  woolen 
underclothing,  little  drafts  of  air  have  no  effect  in  taking 
away  the  heat,  and  so  he  does  not  notice  slight  changes 
of  the  weather.     In  warm  weather  we  wish  to  let  the  heat 
of   the  body  pass  off,   and  so  we  wear  cotton  or  linen. 
Black  cloth  lets  more  of  the  sun's  heat  pass  through  it 
than  white  cloth,  so  white  clothing  is  the  cooler  when  we 
are  exposed  to  the  sun. 

In  winter  we  should  wear  woolen  next  to  the  skin  so  as 
not  to  feel  sudden  changes  of  temperature.  Delicate 
persons  should  wear  woolen  all  the  year. 

When  we  go  from  a  warm  room  into  the  cold  air  we 
should  put  on  an  overcoat  or  wrap  of  some  kind  so  as  to 
avoid  a  sudden  chill.  When  we  work  hard  and  become 
very  warm  we  should  not  stop  to  rest  without  putting  on 
our  coat. 


VENTILATION,    HEAT/ AND   CLOTHJ,NP;)>  ,,   , 

Lying  upon  the  damp  ground  is  dangerous,  for  it  may 
make  our  clothes  damp.  This  will  cool  one  part  of  the 
body  more  than  another  and  cause  us  to  take  cold. 

Bundling  the  neck  and  ears  while  the  legs  and  feet 
have  no  more  covering  than  usual  makes  the  head  tender 
and  often  causes  us  to  take  cold.  Then,  since  our  feet 
are  cold,  we  are  almost  certain  to  take  cold.  We  had 
better  cover  the  feet  more  warmly  and  not  wrap  up  the 
head  and  neck. 

We  ought  always  to  wear  enough  clothing  to  keep  us 
warm.  It  is  a  mistake  to  think  that  we  can  get  used 
to  the  cold  by  going  without  proper  clothes.  We  shall  be 
more  liable  to  take  cold  and  shall  make  ourselves  more 
tender  than  ever.  But  we  ought  not  to  wear  so  much 
clothing  that  we  are  too  warm. 

192.  Tight   clothing.  —  The   blood   carries   heat    to   all 
parts  of  the  body.     When  the  blood  does  not  flow  well 
through  a  part,  that  part  becomes  cold.     If  we  wear  tight 
garters  or  shoes,  the  blood  cannot  flow  through  the  feet 
as  it  should.     Then  we  have  cold  feet.     Tight  clothing 
of  any  kind  makes  us  cold. 

193.  Paper  clothing.  —  If  paper  were  only  stronger,  it 
would  make  one  of  the  best  kinds  of  clothing.     When 
we  have  too  little  clothing  we  can  keep  warm  by  putting 
a  newspaper  around  the  body  under  the  coat  or  waistcoat. 
At  night  a  few  newspapers  between  the  quilts  will  make 
us  much  warmer. 

194.  Cold-blooded  animals.  —  Some  animals,  like   frogs 
and   snakes,    breathe   but   little.      They  do   not    produce 
enough  heat  to  make  themselves  much  warmer  than  the 
air.     On  cold  days  they  are  dull  and  sluggish.     In  winter 
they  are  stiff  and  do  not  move,  but  lie  buried  in  the  mud 
or  earth.     Yet  they  breathe  enough  through  their  skins  to 


3  ,  ,   , .  .  •  •  .-,'•;  ;    APPLIED    PHYSIOLOGY 

keep  themselves  alive.  On  hot  summer  days  they  are 
lively,  for  then  they  can  form  enough  heat  to  keep  them- 
selves warm  and  have  some  left  over  with  which  to  work. 

195.  Alcohol  and  warmth.  —  Heat  is  produced  by  the 
oxidation  of  alcohol.  But  it  would  be  entirely  wrong  to 
think  that  it  makes  the  body  really  warmer.  The  body 
does  not  like  the  heat  which  is  produced  in  this  way,  but 
it  at  once  tries  to  get  rid  of  it  by  sending  more  blood 
through  the  arteries  of  the  skin.  This  makes  the  skin 
warm  and  red,  and  the  drinker  says  that  he  knows  he 
is  warmer  because  he  feels  so.  His  skin  is  really  warmer, 
but  this  is  because  the  heat  is  coming  to  the  surface  and 
is  passing  off.  He  loses  more  heat  than  he  gains.  Often 
his  skin  begins  to  perspire  so  as  to  get  rid  of  still  more 
heat.  Men  are  deceived  by  this  feeling  of  warmth  more 
than  by  any  other  thing  about  alcohol,  and  some  people 
who  will  not  drink  at  any  other  time  will  drink  before 
starting  upon  a  cold  ride.  This  is  the  worst  time  of  all 
to  drink.  It  brings  the  blood  in  contact  with  the  cold  air, 
and  so  more  heat  is  lost.  After  the  heat  from  the  oxida- 
tion of  the  alcohol  has  passed  off,  the  skin  becomes  cold 
once  more,  and  the  body  feels  colder  than  ever.  But  it 
was  really  colder  all  the  time. 

SUMMARY 

1.  The  air  of  inhabited  rooms  is  continually  being  made 

foul  by  the  breath  and  by  vapors  given  off  from 
the  body.    Its  oxygen  is  also  removed  by  breathing. 

2.  We  must  change  the  air  of  a  room  often  enough  to 

keep  away  all  odors  from  the  air. 

3.  Heat   is    produced   by  oxidation    in   the  cells.     This 

warms  the  body  and  also  furnishes  it  with  power  to 
do  work. 


VENTILATION,    HEAT,   AND   CLOTHING  103 

4.  The  skin  gives  off  heat  by  contact  with  the  cool  air 

and  by  its  perspiration. 

5.  Heat  is  always  given  off  at  such  a  rate  as  to  keep  the 

temperature  of  the  body  at  98^  degrees  Fahrenheit. 

6.  When  the  body  is  too  warm  we  have  a  fever  and  are 

sick. 

7.  The  ordinary  feelings  of  cold  and  warmth  are  due  to 

the  state  of  the  nerves  in  the  skin. 

8.  Burning  or  freezing  a  part  kills  the  cells.     Thaw  a 

frozen  part  very  slowly. 

9.  We  should  keep  a  room  warmed  to  about  70  degrees 

Fahrenheit.  » 

10.  Clothing  retains  the  heat  of  the  body,  but  does  not 

make  new  heat.  ^ 

11.  The  oxidation  of  alcohol  develops  heat  in  the  body, 

but  it  causes  more  to  be  given  off  through  the  skin 
than  was  produced. 


CHAPTER   XI 


THE   SKIN  AND   KIDNEYS 

196.    The  derma.  —  The  whole  body  is  covered  with  a 
coat  of  woven  cells  called  the  skin.     The  skin  of  man  is 

from  one  sixteenth  to 
one  eighth  of  an  inch 
in  thickness.  It  is 
made  mostly  of  tough 
cells  like  strings,  and 
contains  more  blood 
tubes  and  nerves  than 
almost  any  other  part 
of  the  body.  This 
thick  part  is  the  true 
skin.  It  is  called  the 
derma  or  cutis.  The 
derma  of  animals  when 
tanned  makes  leather. 

The  nerves  of  the  skin 
end  in  little  pointed 
shoots  of  derma  called 


The  skin  (x  100). 

a  dead  layer  of  epidermis. 
b  growing  layer  of  epidermis. 


c  layer  of  cells  containing  the  coloring  matter     papUfaf       Rows     of 

OT  tnR  Qifin  -*        •* 


of  the  skin. 
d  papilla. 
e  sweat  gland. 
/  small  blood  tube. 
g  fibers  of  the  derma. 
h  fat  cells  in  the  derma. 


pillae  make  the  fine  lines 
upon  the  palms  of  the 
hands.  The  derma  is 
bound  loosely  to  the 
muscles  and  deeper  parts  of  the  body  so  that  it  can  move 

104 


THE   SKIN   AND    KIDNEYS  IO5 

easily.     It  can  be  pinched  up  and  stretched,  but  lies  flat 
and  smooth  again  as  soon  as  it  is  set  free. 

197.  The  epidermis.  —  Upon  the  outside  of   the  derma 
is  a  thin  layer  of  scalelike  cells  called  the  epidermis.     The 
cells  are  called  epithelium.      They  resemble  those  which 
cover  a  mucous  membrane  (see  p.  18).     The  epidermis  has 
no  blood  tubes  or  nerves,  and  so  can  be  cut  or  pricked 
without  bleeding  or  giving  pain.     Its  cells  are  formed  upon 
the  top  of  the  derma  and  are  soft  at  first,  but  as  new  ones 
grow,  the  older  ones  become  hard  and  are  finally  shed  or 
rubbed  off.      These  hard  scales  protect  the  nerves   and 
soft  parts  of  the  skin.     Where  the  epidermis  is  gone  and 
the  nerves  are   touched  directly,  the    part   is   very    sore 
and  tender.    The  papillae  reach  into  the  epidermis  so  as 
to  feel  more  easily. 

Upon  parts  of  the  body  which  are  rubbed,  the  epidermis 
grows  thicker  and  harder,  so  as  to  protect  the  deeper  parts 
better.  This  is  called  a  calhts.  Rubbing  the  skin  too  hard 
hurts  the  deeper  scales  of  the  epidermis,  and  then  water  or 
blood  collects  under  them  and  raises  the  epidermis  into  a 
little  bag  of  fluid  called  a  blister.  In  the  deepest  parts  of 
the  epidermis  there  are  colored  cells  which  give  the  skin 
its  color.  A  negro  is  black  only  in  a  very  thin  layer  of 
the  deepest  part  of  the  epidermis,  and  his  color  is  not  even 
"  skin  deep." 

198.  Nails. — The  cells  of  the  epidermis  at  the  end  of 
each  finger  and  toe  are  matted  together  to  form  a  single 
thick  and  hard  scale  called  a  nail.     The  nails  protect  the 
flesh   and  form  a  kind  of  knife  with  which  we  can  cut 
and  make  marks.     They  also  can  form  a  pair  of  pincers 
with  which  we  pick  up  and  hold  small  things.     The  cells 
of  the  nail  are  formed  nearly  as  far  back  as  the  joint  of 
the  finger  or  toe.     As  new  ones  are  formed  the  nail  is 


io6 


APPLIED   PHYSIOLOGY 


forced  ahead,  and  so  it  grows  long  and  needs  to  be  cut 
off  even  with  the  ends  of  the  fingers,  with  a  sharp  knife  or 
scissors.  When  the  nails  are  bitten  off,  they  are  left  rough 

__,_<7     and    are    likely  to   catch 

-I_  _~  _r  .  —      - "  -1  ~_    jtj     in  the  clothing  and  tear 

away  from  the  flesh. 
Biting  the  nails  also 
makes  the  ends  of  the 
fingers  soft  and  sore. 

199.  Hangnails.- 
Sometimes  a  little  tongue 
of  skin  at  the  root  of 
the  nail  becomes  torn  up 
and  hangs  by  one  end. 
This  is  called  a  Jiang- 
nail.  They  are  some- 
times very  sore,  and  biting 
them  off  makes  them 
worse.  They  should  be  cut  off  close  to  the  skin  with  a 
sharp  knife.  Sucking  the  fingers,  or  biting  the  nails,  is 
likely  to  cause  these  hangnails. 

Dirt  under  the  ends  of  the  finger  nails  is  not  only  untidy, 
but  may  be  poisonous.  The  nails  themselves  are  not  poi- 
sonous, but  the  filth  which  they  carry  may  contain  germs 
of  sickness.  So  we  ought  to  keep  our  nails  clean. 

200.  Hair.  —  Little  tubes  of  epithelium  from  the  epi- 
dermis reach  into  the  derma,  and  as  fast  as  their  cells 
grow  they  are  matted  together  into  a  string  called  a  hair. 
As  new  cells  are  always  forming,  the  old  ones  are  pushed 
out,  and  so  the  hair  grows.  When  a  hair  is  pulled  out, 
the  cells  lining  the  tube  keep  on  growing  and  soon  make 
a  new  hair.  Fine  hair  covers  nearly  all  the  body,  but  upon 
the  head  and  upon  men's  faces,  it  grows  long. 


A  nail  ( x  200) . 

a  surface  of  the  nail. 

b  body  of  the  nail. 

c  epithelial. cells  just  before  they  are  welded 

into  a  nail. 
d  papilla. 
e  growing  epithelium. 


THE   SKIN   AND    KIDNEYS 


TO/ 


At  the  roots  of  the  hair  are  the  openings  of  small  glands, 
which  make  an  oily  substance.  This  oils  the  hair  and 
skin,  and  makes  it  soft  and  glossy.  Each  hair  has  a  little 
muscle,  which  can  pull  upon  the  hair  so  as  to  make  it 
stand  straighter. 
Cold  air  makes 
the  little  muscles 
act,  and  pulls 
the  hairs  of  the 
body  straight 
up,  so  that  their 
roots  form  little 
points  above  the 
flesh.  We  call 
these  points 
goose  flesh. 

201.  Care  of 
the  hair.  —  The 
short  hair  of 
the  body  seems 
to  be  an  aid 'in 
feeling.  The 
hair  of  the  head 
grows  long  for 
ornament  and 
protection.  A  healthy  person  produces  enough  oily  sub- 
stance to  keep  the  hair  soft  and  glossy.  If  the  hair  is 
brushed  so  as  to  keep  it  clean  and  to  spread  the  oil  over 
it,  it  will  look  well  without  using  hair  oil  or  powder.  On 
the  other  hand,  most  hair  oils  and  restoratives  contain 
substances  which  are  harmful.  Hair  dyes  are  still  more 
poisonous.  They  never  make  the  hair  look  natural, 
and  the  lead  which  they  often  contain  may  poison  the 


A  hair  ( x  200) . 

a  epidermis  of  the  skin. 
b  hair  shaft. 

c  sebaceous  or  oil  gland. 
d  muscle  which  makes  the  hair  erect. 
e  epithelium  of  the  hair  root. 
/  fat  cells  in  the  derma. 
g  papilla  from  which  the  hair  grows. 


IO8  APPLIED   PHYSIOLOGY 

body.     The  hair  should  be  washed  as  often  as  it  becomes 
dirty. 

202.  Perspiratory  glands.  —  In  almost  every  part  of  the 
skin  there  are  little  tubes  made  of  cells  of  epithelium,  like 
those  of  the  epidermis.     Their  lower  ends  are  coiled  into 
a  knot,  and  their  outer  ends  open  upon  the  surface  of  the 
epidermis.     Each  tube  is  a  perspiratory  gland.     The  cells 
of    each    gland    make    the   sweat   or  perspiration.     The 
perspiration  is  being  given  off  all  the  time,  and  dries  as 
fast  as  it  forms.     But  if  we  are  too  warm,  it  is  given  off  in 
such  amounts  that  it  collects  in  drops.     About  a  quart  is 

!    produced  every  day,  and  much  more  on  a  hot  day. 

203.  The  perspiration.  —  The  perspiration  is  nearly  all 
water.     A  little  mineral  matter  and  some  oxidized  waste 
matter  are  dissolved  in  it.     You  have  already  learned  that 
the  perspiration  takes  away  the  extra  heat  when  we  are 
too  warm.     This  is  the  main  use  of  the  perspiration.     It 

\  also  takes  away  some  waste  matters  of  the  body. 

204.  The  waste  of  the  body.  —  We  will  now  study  how 
these  waste  matters  are  given  off.     All  oxidation  within 
the  body  produces  carbonic  acid  gas  and  water.     The  car- 
bonic acid  gas  is  of  no  use  in  the  body,  but  passes  off  as 
waste  through  the  lungs.    A  great  deal  of  water  must  pass 
off  from  the  body,  so  as  to  wash  away  the  waste  matter. 
Water  is  found  in  everything  which  the  body  gives  off. 

The  oxidation  of  albumin  produces,  in  addition  to  the 
water  and  carbonic  acid  gas,  another  substance  which  we 
call  urea.  Urea  is  a  poisonous  waste  substance,  and  must 
be  removed  as  fast  as  it  is  formed.  If  oxidation  is  incom- 
plete from  lack  of  oxygen  or  other  causes,  other  substances 
like  urea  are  formed.  Many  of  these  substances  are  ex- 
tremely poisonous.  Urea  and  all  substances  like  it  are 
given  off  by  the  perspiratory  glands,  and  also  by  another 


THE   SKIN   AND   KIDNEYS 

,  set  of  tubes  called  the  kidneys.     The  waste  mineral  matter 
of  the  body  also  passes  off  by  the  skin  and  kidneys. 

205.  The  kidneys.  —  The  kidneys  are  two  bean-shaped 
bodies,  lying  one  on  each  side  of  the  backbone,  underneath 
the  lowest  ribs.     Each  kidney  is  made  of  coils  of  very  fine 
tubes  lined   with    epithelial   cells.     These   cells    separate 
the    urea,  mineral    matters,    and   water   from    the    blood, 
and  pour  the  whole  into  a  single  tube  which  goes  to  the 
bladder. 

206.  Urea  in  the  perspiration.  —  The  perspiratory  glands 
of  the  skin  also  separate  urea,  mineral  matter,  and  water 
from  the  blood.     The  kidneys  get  rid  of  many  times  as 
much  urea  and  mineral  matters  as  the  skin,  but  the  skin 
gives  off  nearly  as  much  water  as  the   kidneys.     Some- 
times the  kidneys  get  diseased,  so  that  they  cannot  get  rid 
of  the  urea.     Then  the  whole  body  is  poisoned,  and  the 
kind  of  disease  called  Bright 's  disease  comes  on.     Then 
the  skin  may  give  off  much  more  than  its  natural  amount 
of  urea,  until  the  kidneys  are  able  to  do  their  work  again. 

207.  Need  of  bathing.  —  The  water  of  perspiration  dries 
off  from  the  skin  and  leaves  the  urea  and  mineral  matters 
behind.     The  outside  of  the  epithelium  becomes  dead,  and  ' 
part  is  worn  off,  and  part  stays  upon  the  skin.     All  kinds' 
of  dust  and  dirt  also  stick  to  the  skin,  and  stop  its  glands 
so  that  the  waste  matters  cannot  pass  off  as  they  should. 
So  the  skin  needs  to  be  bathed.     Owing  to  the  oil  in  the 
skin,  water  alone  will  not  always  remove  the  dirt,  and  so 
plenty  of  soap  is  needed.     When  there  is  an  unpleasant 
odor  about  the  skin,  it  certainly  needs  a  bath. 

In  summer,  when  we  perspire  and  the  air  is  full  of  dust, 
we  need  a  bath  more  often  than  in  winter.  It  does  not 
matter  how  the  bath  is  taken,  so  long  as  we  wash  well. 
We  can  get  clean  by  using  a  common  basin.  Bathing  the 


110  APPLIED   PHYSIOLOGY 

whole  body  every  week  in  winter  and  two  or  three  times  a 
week  in  summer  will  keep  most  persons  clean. 

208.  Too   much  washing.  —  Some  persons  soak  them- 
selves in  hot  water  and  rub  the   skin   for  a  long  while. 
Soaking  in  hot  water  loosens  and  kills  the  epidermis,  and 
then  by  rubbing,  it  can  be  made  into  little  rolls.     These 
rolls  are  not  dirt,  but  are  the  epithelium,  which  is  a  coat  to 
keep  us  warm  and  to  keep  the  deeper  parts  of  the  skin 
from  being  hurt.     We  can  rub  this  epithelium  off  as  long 
as  any  is  left. 

209.  Cold  baths.  —  A  cold  bath  drives  the  blood  away 
from  the  skin  at  first,  but  in  a  moment  it  comes  back,  and 
we  feel  warm  again.     The  heart  beats  with  greater  vigor, 
and  we  feel  refreshed  by  the  bath.     If  we  stay  in  too  long, 
the  blood  does  not  come  back  to  the  skin  and  we  feel  cold 
and  weak.     A  cold  bath  every  morning  upon  first  getting 
up  makes  us  feel  warm  and  refreshed.     But  a  weak  per- 
son cannot  stand  a  cold  bath.     No  one  should  stay  in  the 
water  after  he  begins  to  feel  cold. 

210.  Hot  baths.  —  A  hot  bath  causes  more  blood  to  flow 
through  the  skin,  but  does  not  make  the  heart  stronger. 
Less  blood  passes  through  the  brain  and  deeper  parts  of 
the  body,  and  we  feel  weak  and  sleepy.     Often  we  feel 
cold  after  it.     The  best  time  to  take  a  hot  bath  is  when 
we  are  going  to  bed. 

211.  A  fair   skin.  —  Bathing   keeps   the  skin  fair  and 
smooth,  but  neither  bathing  nor  anything  else  will  make  it 
fair  if  the  waste  matters  which  circulate  in  the  blood  are 
not  given  off  in  the  right  way.     The  best  way  to  keep  the 
skin  fair  is  to  arrange  our  food  and  habits  so  that  there  is 
only  a  small  amount  of  waste  matter  to  be  given  off.     If 
we  eat  only  plain  food,  slowly,  and  at  mealtimes,  and  in 
the  right  amounts,  our  food  will  digest  as  it  should,  and 


THE   SKIN   AND   KIDNEYS  III 

will  be  taken  into  the  blood  and  be  oxidized  in  the  right 
way.  Then  the  kidneys  and  skin  will  always  do  their  work 
well.  This  is  why  you  are  so  often  told  that  you  must 
keep  your  stomach  in  good  order  if  you  wish  to  have  a 
fair  skin.  Paint  and  powder  are  merely  a  kind  of  dirt; 
they  stop  the  action  of  the  skin,  and  bnly  make  it  look 
worse  than  ever. 

212.  Washing  clothes.  —  The  waste  matters  of  the  skin 
are  rubbed  off  upon  our  clothes  and  bedclothes.     These 
become  dirty  and  must  be  washed.     Air  and  the  sun  have 
great  power  of  destroying  waste  matters  of  the  body.     At 
night  all  our  clothes  should  be  taken  off  and  put  where  the 
air  can  get  at  them,  and  we  should  sleep  in  a  clean  night 
dress.     In  the  daytime  our  beds  should  be  aired,  and  the 
clothes  and  blinds  opened  so  that  the  sunlight  can  reach 
the  room  and  destroy  the  waste  matter. 

The  water  and  waste  matters  of  the  body,  and  the  water 
used  in  washing  and  bathing,  all  contain  poisonous  matter. 
If  it  is  thrown  upon  the  ground  it  may  soak  into  the  well 
and  poison  the  drinking  water,  or  its  gases  may  make  the 
air  unfit  for  breathing.  The  water  used  by  a  person  who 
has  a  catching  disease  is  very  dangerous,  for  the  germs  of 
the  disease  can  grow  outside  the  body  and  cause  the  dis- 
ease in  the  next  person  who  gets  the  germs.  All  water 
and  slops  ought  to  be  carried  away  from  the  house  and 
emptied  into  a  deep  hole  in  the  ground.  Then  the  soil 
will  soon  kill  all  the  poisonous  germs. 

213.  What  to   do  with   slops.  —  Small  families  in  the 
country  often  throw  their  slops  out  of  the  back  door,  but 
it  is  not  safe  to  do  this,  for  some  may  run  into  the  well  and 
poison  the  water.    A  well  ought  to  be  dug  on  ground  higher 
than  the  kitchen  and  barn.     Hard  rock  or  clay  sloping 
toward  the  well  may  carry  slops  underground  into  the  well 


112  APPLIED   PHYSIOLOGY 

(see  page  32).  It  is  as  dangerous  to  use  such  impure  water 
for  washing  as  for  drinking.  In  cities  the  slops  are  carried 
away  in  pipes  called  sewers.  They  empty  into  the  rivers 
or  into  the  sea,  and  their  waste  matters  are  washed  away. 
Sewers  give  off  a  foul  gas,  and  great  care  is  needed  to 
prevent  its  getting  into  our  houses. 

214.  Effects  of   alcohol  upon  the  kidneys.  —  From   the 
time  alcohol  is  swallowed  it  causes  more  waste  matters  to 
be  formed.     It  hinders  digestion,  so  that  the  food  does  not 
reach  the  liver  in  the  right  form.     The  liver  is  overworked 
in  changing  the  food  to  blood,  and  lets  some  through  half 
changed,  and  even  lets  poisons  pass  through.     Then,  in 
the  liver,  alcohol  appropriates  oxygen  and  the  food  is  not 
properly  oxidized,  but  still  more  poisons  are  made.     The 
kidneys  and  skin  try  to  get  rid  of  these  poisons,  and  may 
do  it  for  a  long  while,  but  they  become  overworked  and 
finally  fail,  and  then  Bright's  disease  comes  on.     Alcohol 
makes  more  kidney  trouble  than  all  other  causes  put  to- 
gether ;  in  fact,  it  is  almost  impossible  to  drink  for  a  long 
time  without  bringing  on  kidney  disease. 

215.  Alcohol  and  the  skin.  —  Alcohol  causes  an  increased 
flow  of  blood  through   the  skin,   making  it  redder  than 
usual.     After  a  few  weeks  of  drinking,  the  skin  and  eyes 
remain  red  continuously,  and  their  cells  do  not  receive 
proper  nourishment  from  the  blood.     These  effects  are 
seen  upon  the  face  more  than  anywhere  else.     Its  skin 
is  often  rough  or  spotted,  or  covered  with  pimples.     Often 
the  nose  becomes  thicker  and  larger.     All  these  things 
give  the  skin  a  very  unpleasant  appearance,  but  they  indi- 
cate the  condition  of  the  whole  body.     A  skin  which  is 
weakened  by  alcohol  cannot  do  the  work  of  the  kidneys, 
and  kidney  disease  in  drinkers  is  much  harder  to  cure 
than  in  those  whose  skins  are  in  good  order. 


THE   SKIN   AND   KIDNEYS  113 

SUMMARY 

1.  The  skin  is  made  of  a  thick,   tough  part  called  the 

derma,  and  a  thin  protective  covering  of  epithelium 
called  the  epidermis. 

2.  The  derma  contains  blood  tubes,  nerves,  and  perspira- 

tory glands. 

3.  The  epidermis  protects  the  derma  and  forms  the  nails 

and  hair. 

4.  Oxidation  of  albumin  makes  a  substance  called  urea, 

which  must  be  given  off  from  the  body.  Urea  and 
carbonic  acid  gas  are  the  main  waste  substances  of 
the  body. 

5.  The  kidneys  and  perspiratory  glands  are  coils  of  fine 

tubes,  made  of  epithelial  cells,  which  take  water, 
urea,  and  mineral  matters  from  the  blood. 

6.  We  must  bathe  our  bodies  and  wash  our  clothes  so 

as  to  wash  away  the  waste  matters  from  the  skin. 

7.  Slops  must  be  carried  away  from  the  house  so  that  the 

poisonous  matter  will  neither  get  into  the  well  nor 
make  foul  gases. 

8.  Alcohol  causes  poisons  to  be  formed  in  the*  body  which 

the  kidneys  try  to  throw  off,  but  they  become  over- 
worked and  diseased  in  the  attempt. 

9.  Alcohol  weakens  the  skin  so  it  cannot  help  the  kidneys 

get  rid  of  the  waste  matter.     It  also  gives  the  skin 
an  unpleasant  appearance, 
ov.  PHYSIOL.  (INTER.)  —  8 


CHAPTER   XII 
THE  NERVES  AND  SPINAL  CORD 

216.  Cells  act  together.  —  We  have  seen  that  the  cells 
of    the   body   eat   and   breathe,    and   that   oxygen   burns 
their   food   and   bodies,   produces  heat,    and   gives   them 
power  for  their  work.     Each  cell  is  thus  a  complete  ani- 
mal, like  the  ameba.    But  millions  of  amebas  tied  together 
in  the  shape  of  the  body  would  not  act  like  a  man,  for 
no  two  would  act  together,  but  they  would  fight  and  strive 
to  get  away  from  each  other.     The  cells  of  the  body  are 
tied  together  by  strings  of  connective  tissue.     But  they  are 
well-trained  servants,  and  all  obey  the  mind.     They  work 
so  well  together  that  we  do  not  think  of  our  bodies  being 
made  of  separate  cells. 

217.  Nerves.  —  The  mind  lives  in  a  few  cells  and  rules 
all  the  rest.     From  these  cells,  little  threads  called  nen>es 


A  nerve  thread  (X  400). 
a  central  conducting  fiber.  b  covering  of  fat. 

go  to  every  part  of  the  body  and  touch  every  cell.  The 
mind  and  the  cells  talk  to  each  other  over  these  threads, 
just  as  you  can  talk  to  a  friend  over  the  telephone.  A 
nerve  thread  is  like  a  very  fine  wire  covered  with  a  kind 
of  fat.  It  is  so  small  that  a  microscope  is  needed  to  see  it. 
Many  of  these  threads  run  together  in  bundles,  which  we 

114 


THE  NERVES  AND   SPINAL  CORD 


a 


A  thin  slice  from  the  end  of  a  cut 
nerve  ( X  200) . 

a  nerve  thread. 

b  connective    tissue    binding    the 
threads  into  a  cord. 


call  nerves.     In  the  upper  part  of  the  arm  or  leg  they  are 

as  large  as  a  knitting  needle,  and  grow  smaller  as  threads 

are  given  off  to  the  cells.    There 

are  more  of  these  nerves  in  the 

skin  than  in  any  other  part  of 

the    body,    but    yet    a    thread 

reaches  every  cell  of  the  body. 

218.  Motor    nerve    messages. 
—  Nerves   can   carry  messages 
both  from  the  mind  to  the  cells, 
and  from  the  cells  to  the  mind. 
The   mind   sends    messages    to 
the  cells  for  each  to  do  its  own 
kind  of  work.     Thus  it  tells  the 
muscle  cells  to  move   the   arm 

or  leg.  It  tells  the  salivary  glands  to  make  saliva  and 
pour  it  into  the  mouth.  It  tells  the  liver  cells  to  change 
digested  food  to  blood. 

The  mind  also  tells  every  cell  in  the  body  how  much  to 
eat,  and  how  much  oxygen  to  breathe.  The  cells  can  eat 
and  breathe  without  being  told  by  the  mind,  but  if  the 
nerves  do  not  bring  the  messages  from  the  brain,  the  cells 
do  as  they  please  about  eating,  and  sometimes  get  lazy  and 
hardly  eat  or  breathe  at  all,  but  waste  away  as  in  a  para- 
lyzed man. 

Nerves  which  carry  messages  from  the  brain  to  the  cells 
are  called  motor  nerves,  for  orders  to  move  or  change  in 
shape  are  often  sent  to  the  cells.  These  messages  are 
continually  coming  and  going,  and  when  they  stop,  life 
ends  at  once. 

219.  Sensory  nerve  messages.  —  The  cells  of  the  body 
also  send  messages  of  their  state  and  needs.     They  send 
messages  to  the  mind  whenever  anything  touches  them. 


Il6  APPLIED    PHYSIOLOGY 

The  message  to  the  mind  is  called  a  feeling  or  sensation. 
The  cells  send  such  true  news  of  everything  which  they 
touch  that  the  mind  depends  upon  it  wholly  for  news  of 
the  outer  world,  and  is  seldom  deceived.  When  something 
touches  the  cells  so  as  to  hurt  them,  the  mind  feels  the 
message  as  a  pain.  Then  the  mind  tells  the  muscle  cells 
to  pull  the  cells  away  from  the  thing  which  hurts  them. 
Pain  is  a  good  thing,  for  it  not  only  tells  us  when  we  are 
being  harmed,  but  it  also  makes  us  get  away  from  danger. 

The  cells  of  the  body  also  send  word  when  they  are 
hungry  or  thirsty.  This  is  different  from  the  hunger  and 
thirst  which  we  feel  in  the  mouth,  and  which  is  only  the 
message  of  the  stomach  that  it  is  empty.  Each  cell  of 
the  body  calls  for  food,  and  the  mind  supplies  it  by  causing 
the  arteries  to  become  larger  so  as  to  supply  them  with 
more  blood.  Each  cell  also  sends  word  to  the  mind  when 
it  is  tired  and  needs  rest. 

A  nerve  which  carries  messages  to  the  brain  is  called  a 
sensory  nerve,  because  we  feel  many  of  the  messages.  We 
do  not  feel  the  message  as  it  passes  over  the  nerve,  but 
only  when  it  reaches  the  mind  in  the  brain. 

220.  False  messages.  —  Sometimes  false  messages  are 
sent.  If  a  nerve  is  pinched  or  hurt  in  its  course,  the  mind 
feels  the  message  as  if  it  came  from  the  end  of  the  nerve. 
When  we  pinch  the  nerve  which  makes  the  funny  bone  in 
the  elbow,  it  seems  to  the  mind  that  the  little  finger  is  hurt. 
When  the  nerves  at  the  knee  are  squeezed,  as  when  you 
sit  with  your  legs  crossed  for  some  time,  they  cannot  carry 
the  messages  from  the  foot,  and  so  we  say  that  the  foot  is 
asleep. 

When  the  surgeon  cuts  your  flesh,  you  feel  great  pain. 
So  he  puts  a  little  cocaine  upon  the  nerve  through  a  hollow 
needle.  The  cocaine  keeps  the  nerves  from  sending  the 


THE  NERVES   AND    SPINAL  CORD 


news  of  the  cut  to  the  brain,  and  you  do  not  feel  pain 
when  you  are  cut.  In  a  little  while  the  blood  washes  away 
the  cocaine,  and  you  can  feel  again. 

221.  How  fast  nerve  messages  travel.  —  The  nerves  can 
carry  messages  about  one  hundred  feet  each  second,  or  a 
little  faster  than  an  express  train.     In  the  time  between 
two  ticks  of  a  watch,  news  of  a  pin  prick  can  travel  from 
the  foot  to  the  brain,  and  the  mind  can  send  word  back 
for  the  muscles  to  move  the  foot  away  from  the  pin.     If 
your  arm  were  long  enough  to  touch  the  sun,  you  would 
die  of  old  age  before  the  feeling  of  the  burn  could  reach 
you. 

222.  The  spinal  cord.  —  As  we  follow  the  nerves  back- 
ward, we  can  trace  them  into  the  inside  of  the  backbone, 
where  they  seem  to  come 

from  a  white  string  of 
flesh  called  the  spinal 
cord. 

The  spinal  cord  is  a 
soft  cord  about  eighteen 
inches  long,  and  about 
the  size  of  the  end  of 
the  little  finger.  It  is 
hung  in  the  middle  of 
the  rings  of  bone  which 
make  up  the  backbone. 
When  it  is  cut  across,  its  end  looks  like  a  white  ring 
around  a  gray,  butterfly-shaped  center.  In  the  gray 
matter  are  cells  in  which  a  part  of  the  mind  lives.  The 
white  matter  is  made  of  nerve  threads  like  those  in  the 
body.  Some  stop  at  the  cells  of  the  spinal  cord;  others 
go  on  to  the  brain ;  and  still  others  start  at  the  cells  of  the 
cord  and  end  in  the  brain. 


A  thin  slice  from  the  spinal  cord  with  the 
cells  and  nerves  magnified  200  diameters. 

a  cells  in  the  gray  matter. 

b  fibers  in  the  gray  matter. 

c  nerve  threads  in  the  white  matter. 


n8 


APPLIED   PHYSIOLOGY 


223.  How  the  spinal  cord  acts.  —  The  mind  in  the  cells 
of  the  spinal  cord  is  like  a  telegraph  operator,  who  does 
not  send  messages  except  as  others  tell  him  to.     In  the 
first   place,  the   mind   in   the  brain   sends  all  its  orders 
through  its  servants,  the  cells  of  the  spinal  cord.     When 
it  wishes  to  move  the  hand,  it  sends  word  to  the  cells  of  the 
spinal  cord,  and  they  send  word  to  the  muscles  of  the  arm 
so  quickly  that  we  do  not  know  that  they  had  anything  to 
do  with  moving  the  arm. 

224.  Reflex  acts.  —  In  the  second  place,  the  spinal  cord 
sends  orders  when  asked  to  do  so  by  the  cells  of  the  body. 


Diagram  of  reflex  action. 

a  tack  pricking  the  hand.          b  sensory  nerve.          c  nerve  cell  in  the  spinal  cord. 
d  motor  nerve.        e  muscle  moving  the  hand  away  from  the  tack. 

The  nerves  which  carry  the  messages  from  the  cells  of  the 
body  go  to  the  cells  of  the  spinal  cord,  and  also  to  the 
brain.  The  cells  of  the  spinal  cord  are  much  nearer 
the  cells  of  the  body  than  the  brain  is,  and  when  they  get 
word  that  anything  has  harmed  a  part  of  the  body,  they 
have  the  power  to  order  the  muscles  to  snatch  that  part 
away  without  waiting  for  word  from  the  brain.  Thus,  when 
the  cord  receives  word  that  the  hand  touches  a  hot  stove, 
it  at  once  sends  an  order  for  the  muscles  to  snatch  the 
hand  away,  and  it  is  done  by  the  time  the  brain  feels 
the  burn.  When  anything  suddenly  hurts  you,  you  cannot 


THE  NERVES   AND   SPINAL  CORD 


119 


help  jumping  away.     This  is  called  a  reflex  act,  because 
the  pain  seems  to  be  reflected  back  as  motion. 

225.  Orders  for  the  growth  of  cells.  —  The  spinal  cord 
also  sends  most  of  the  orders  for  the  cells  to  eat  and  grow, 
and  for  the  glands  to  work,  and  for  the  arteries  to  become 
large  or  small,  as  each  part  of  the  body  has  need  of  blood. 
These  are  nearly  all  reflex  acts.     When  the  cells  of  the 
stomach  feel  food  touching  them,  they  tell  the  spinal  cord, 
and  it  sends  word  to  the  glands  to  pour  out  gastric  juice. 

226.  The  sympathetic  nervous  system.  —  The  spinal  cord 
sends  its  orders  for  the  growth  of  cells,  for  digestion,  and 
for  the  flow  of  blood  through  a  minor  set  of  nerve  cells 
and  fibers.     There  are  several  small  collections  of  nerve 
cells  arranged  mostly  in  a  double  row  down  the  front  of 
the  backbone.    Each  collection  looks  like  a  grain  of  wheat 
and  is  called  a  ganglion.     From  the  ganglia  fine  nerves 
go  to  the  different  arteries  and  glands,  and  to  the  stomach 
and  intestine.     The  ganglia  are  also  connected  with  the 
spinal  cord  and  derive  most  of  their  power  from  it.     They 
are  really  its  servants,  just  as  the  cord  itself  is  the  servant 
of  the  brain.     The  ganglia  and  nerves  are  called  the  sym- 
pathetic system. 

The  sympathetic  system  sends  its  orders  slowly  and  regu- 
larly. It  has  but  little  sensation,  and  is  but  slightly  affected 
by  outside  influences.  So  ordinary  causes  will  not  disturb 
digestion  or  the  flow  of  blood. 

227.  Acquired  reflex  acts.  —  In  order  that  the  brain  may 
be  able  to  do  more  work,  it  is  continually  teaching  the 
spinal  cord  how  to  send  the  proper  messages  alone.    When 
a  baby  first  learns  to  walk,  its  brain  has  to  tell  the  spinal 
cord  just  how  far  to  order  the  feet  to  be  moved,  and  when 
and  in  what  direction.     So  it  is  hard  and  slow  work  for 
the  baby  to  walk,  but  in  a  little  while  the  spinal  cord  learns 


120  APPLIED   PHYSIOLOGY 

to  send  the  orders  alone,  and  thus  walking  becomes  a  reflex 
act.  So  in  learning  any  new  motion,  after  we  have  done 
it  a  few  times  our  spinal  cords  send  the  proper  order  with- 
out our  thinking  of  it. 

228.  Need  of  the  spinal  cord. — The  spinal  cord  acts 
without  our  knowledge.  We  do  not  feel  the  cells  of  the 
body  grow,  and  we  do  not  feel  the  spinal  cord  send  the 
orders  for  their  growth.  It  controls  all  the  vital  actions 
of  life.  It  is  well  we  do  not  have  to  think  about  sending 
the  orders  for  living,  for  we  might  forget  them  and  then 
we  should  die.  As  it  is,  the  cord  attends  to  them  wholly 
without  our  knowledge.  We  put  food  into  our  stomachs 
and  the  spinal  cord  sees  that  it  is  made  into  living  cells 
and  that  the  cells  do  their  work.  We  cannot  change  its 
work  by  any  amount  of  thought  or  effort.  An  animal's 
spinal  cord  does  its  work  as  well  as  a  man's.  In  fact,  it 
has  the  same  kind  of  work  to  do  and  is  as  perfect  as  man's. 

SUMMARY 

1.  Nerves  carry  messages  from  the  mind  to  the  cells  of 

the  body,  telling  them  to  act  and  to  eat.  The  cells 
also  send  messages  to  the  mind,  telling  of  their  needs 
and  of  what  is  touching  them. 

2.  Nerves  begin  in  the  spinal  cord. 

3.  The  spinal  cord  is  itself  made  of  nerve  threads,  and 

also  of  cells  in  which  a  part  of  the  mind  lives. 

4.  The  nerve  cells  of  the  spinal  cord  send  messages  over 

the  nerves  when  told  by  the  mind  in  the  brain. 

5.  The  cells  of  the  spinal  cord  also  send  orders  in  response 

to  information  brought  by  the  nerves.  This  is  called 
a  reflex  action.  Orders  to  grow  and  to  snatch  the 
body  from  a  sudden  danger  are  reflex  acts. 


THE  NERVES  AND   SPINAL  CORD  121 

6.  In  sending  orders  for  the  preparation  of  food  and  the 

growth  of  cells,  the  spinal  cord  acts  through  another 
set  of  nerve  cells  and  fibers  called  the  sympathetic 
system. 

7.  The  sympathetic  system  sends  fine  nerves  to  the  mus- 

cles of  the  arteries  and  of  the  intestine.  It  acts 
under  the  control  of  the  spinal  cord. 


CHAPTER   XIII 

THE   BRAIN 

229.  The  brain.  —  The  mind,  which  is  the  real  man,  and 
which  feels,  thinks,  and  makes  our  bodies  move,  lives  in 
the  brain.     The  brain  lies  in  the  top  of  the  head  and  is 
covered  with  the  bones  of  the  skull.     It  is  a  soft,  white 
mass  weighing  about  three  pounds. 

230.  The  medulla.  —  The  brain  is  made  of  three  main 
parts.    Just  above  the  spinal  cord  is  a  small,  wedge-shaped 

part  called  the  medulla 
oblongata.  The  medulla 
is  a  part  of  the  spinal 
cord  as  well  as  of  the 
brain.  It  gives  off  nerves 
to  the  head  just  as  the 
spinal  cord-  gives  them 
to  the  rest  of  the  body. 
In  it  is  a  little  bundle  of 
nerve  cells  which  send 
out  the  orders  for  the 
body  to  breathe.  When 
these  cells  are  hurt,  breathing  stops  at  once  and  the  body 
dies.  So  the  medulla  is  often  said  to  be  the  seat  of  life. 

231.  The  cerebellum.  —  Above  the  medulla  is  a  round 
part  of  the  brain  called  the  cerebellum.     It  neither  sends 
orders  nor  feels,  but  in  some  unknown  way  it  helps  the 
rest  of  the  brain  so  that  they  send  out  better  orders  for 


*<*. 


Human  brain  cut  crosswise. 


THE   BRAIN 


123 


walking  and  standing  upright,  and  for  all  motions  in  which 
the  body  must  make  exact  movements.  A  bird  or  dog 
without  its  cerebellum  cannot  run  or  stand,  but  flutters  or 
rolls  about  the  floor.  Yet  it  is  strong  and  acts  all  right 
in  other  ways. 

232.    The  cerebrum.  —  The  uppermost  part  of  the  brain 
is  the  cerebrum.     It  is  about  four  times  as  large  as  all  the 


dflez 


ion. 


Regions  of  the  head  and  action  of  the  different  parts 
of  the  brain. 

rest  together.  Its  inside  is  white  matter  and  is  made  of 
nerve  threads.  Over  the  white  matter  is  a  covering  of 
gray  matter  which  looks  as  if  it  were  too  large  and  so  is 
folded  and  puckered.  The  gray  matter  has  many  nerve 
cells.  The  mind  lives  in  these  nerve  cells.  The  nerves 
of  the  white  matter  join  these  cells  and  connect  them  with 
the  spinal  cord  and  with  the  nerves  of  the  body. 


124  APPLIED   PHYSIOLOGY 

233.  The  senses.  —  The  cells  of  the  body  are  continually 
sending  news  of  their  own  state  to  the  spinal  cord.     The 
brain  feels  the  news  only  when  it  is  very  great  in  amount, 
as  when  the  body  is  hungry  or  thirsty  or  tired. 

The  cells  also  send  messages  telling  what  is  affecting 
them  from  the  outside.  This  news  goes  to  the  brain  and 
produces  a  feeling,  while  it  only  slightly  affects  the  spinal 
cord.  We  get  news  of  the  outside  world  by  means  of  see- 
ing, hearing,  feeling,  smelling,  and  tasting.  'These  five 
kinds  of  news  are  called  the  senses. 

234.  Location   of    the   senses.  —  Feelings   of   sight   are 
brought  to  the  cells  of  the  brain  under  the  lower  and  back 
part  of  the  head.      Messages  of   sound,  smell,  and  taste 
reach  the  mind  in  the  cells  just  above  the  ears.     We  feel 
a  touch  or  pain  by  means  of  the  cells  under  the  top  part 
of  the  head.    This  means  that  if  the  back  part  of  the  brain 
is  injured,  we  can  no  longer  see.     In  the  same  way,  an 
injury  to  any  part  of  the  brain  deprives  us  of  the  sense 
which  is  located  there. 

235.  Motion.  —  Besides  feeling,  we  can  also  move  our 
bodies  as  we  wish.     The  orders  for  moving  are  sent  from 
the  brain  down  the  spinal  cord,  and  out  along  the  nerves, 
to  the  muscles.     They  cause  the  muscles  to    move   the 
body.     That  part  of  the  brain  under  the  top  of  the  head 
in  front  of  the  ears  sends  the  orders  for  motion.     If  this 
part  of  the  brain  is  hurt,  we  cannot  move  so  much  as  a 
finger,  even  if  we  can  feel  and  have  a  full  knowledge  of 
what  touches  it.     Each  muscle  has  its  own  set  of  cells  in 
the  brain.     These  do  the  same  things  in  both  man  and 
animals. 

236.  Memory.  —  When  a  cell  of  the  brain  receives  a 
message,  it  lays  it  away  so  that  it  can  find  it  again.     A 
message  stored  away  for  use  is  a  memory.     We  remember 


THE   BRAIN  125 

how  pleased  we  felt  when  we  heard  the  band  play,-  and 
how  our  ears  ached  when  we  were  out  in  the  blizzard. 
We  can  also  remember  the  messages  which  the  brain  has 
sent  out.  Thus  we  remember  how  hard  we  had  to  run  to 
catch  the  train,  and  that  we  had  to  make  our  arms  move 
in  a  certain  way  in  order  to  throw  a  stone  against  a  mark. 

237.  Association  of  cells.  —  Each  cell  in  the  brain  is  con- 
nected with  all  the  other  cells  through  the  nerve  threads 
of  the  white  matter.     So  when  we  remember  one  thing  we 
at  once  think  of  something  else  about  it.     Thus  one  set 
remembers  that  it  saw  a  field  of  large  ripe  blackberries ; 
another  set  of  cells  remembers  how  good  these  tasted ; 
another  set  remembers  hearing  a  dog  make  a  great  noise ; 
and  still  another  set  of  cells  remembers  how  fast  it  made 
the  legs  run  to  take  the  body  away  from  the  berries. 

238.  Thinking.  —  The  minds  of  all  animals  can  feel  as 
well  as  a  man's  mind,  or  better,  and  can  often  make  their 
bodies  move  more  swiftly  and  more  gracefully  than  man's. 
But  the  mind  can  do  more  than  feel  and  cause  the  body 
to  move.     It  can  think  about  what  it  remembers.     It  thinks 
that  some  things  were  right  and  some  wrong,  or  that  we 
could  have  done  better  if  we  had  acted  in  a  different  way. 
It  plans  to  do  things  better  next  time.     An  animal  does 
very  little  thinking;  so  we  say  that  it  has  no  mind.     It 
seldom  plans  ahead  and  does  not  learn  new  things  easily. 
Yet  some  dogs  and  horses  use  almost  as  much  thought  as 
some  men. 

239.  Where  thinking  is  done.  —  Thinking  is  done  by  the 
cells  of   the  brain  behind  the  forehead.     Animals  have 
very  small  foreheads,  and  so  their  minds  cannot  think  to 
any  extent.     While  most  of  the  cells  of  the  brain  can  act 
from  the  time  a  child  is  born,  the  thinking  cells  must  be 
taught  how  to  act.     Boys  and  girls  go  to  school  so  as  to 


126  APPLIED   PHYSIOLOGY 

teach  the  cells  of  the  forehead  how  to  think.  The  cells 
of  the  rest  of  the  brain  may  know  how  to  feel  and  see 
and  hear,  and  how  to  make  the  body  move,  and  may  have 
wonderful  things  stored  in  memory,  but  if  the  forehead 
cells  do  not  know  how  to  think,  the  mind  cannot  make 
use  of  the  memories.  We  say  that  such  a  person  is  a 
fool,  even  though  he  has  great  knowledge.  In  school  it 
is  of  little  account  how  many  things  are  stored  away  in 
the  memory,  for  we  can  get  memories  anywhere.  But  in 
school  we  should  learn  how  to  use  memories,  and  how  to 
tell  which  ones  are  best  and  right  for  the  work  we  wish 
to  do. 

240.  How  tp  think.  —  The  only  way  to  teach  the  cells 
under  the  forehead  is  to  make  them  work  at  one  thing  at 
a  time  until  they  can  do  it.     When  a  boy  wants  to  get  his 
lesson  upon  the  reason  for  the  temperature  at  the  North 
Pole,  he  cannot  do  it  if  he  thinks  a  minute  of  the  North 
Pole,   and   then   a   minute    about   snowballing,  and   then 
another  minute  of  baseball,  and  then  goes  at  the  North 
Pole  again.     But  this  is  the  way  boys  and  girls  naturally 
do,  and  only  a  few  succeed  in  training  their  foreheads  to 
think  of  one  thing  at  a  time.     To  learn  to  think  well  re- 
quires great  effort,  kept  up  for  a  long  time.     A  man   is 
educated  when  he  can  use  all  the  power  of  his  mind  in 
thinking  of  one  thing  at  a  time.     If  a  boy  thinks  of  kites 
when  he  is  studying  geography,  he  must  get  back  to  his 
geography  as  quickly  as  he  can.     He  will  like  his  kites 
all  the  more  when  he  gets  his  lesson,  for  he  will  be  more 
likely  to  put  his  whole  mind  upon  them. 

241.  Speech.  —  The  highest  act  of  the  mind  is  speech. 
The  lips  and  tongue  can  be  moved  when  ordered  by  the 
brain  cells  above  the  ears,  but  if  they  move  so  as  to  pro- 
duce speech,  the  orders  must  be  sent  by  a  special  set  of 


THE   BRAIN  I2/ 

nerves  in  the  lower  part  of  the  brain  just  above  and  in 
front  of  the  left  ear.  When  this  part  of  the  brain  is  de- 
stroyed, a  person  cannot  talk,  but  he  can  still  make  a  noise 
with  his  mouth  and  understand  speech,  for  the  hearing 
part  of  his  brain  is  whole.  He  can  also  read  and  write, 
for  these  parts  of  his  brain  are  also  whole. 

242.  Use  of  speech.  — The  power  of  speech  accounts  for 
the  great  difference  between  man  and  animals.     Animals 
must  learn  everything  through  their  senses.     They  can- 
not tell  one  another   how  to    do   certain   things.      They 
cannot  tell  their  knowledge  to  their  young. 

Men  know  far  more  things  than  they  have  learned  by 
their  senses,  for  they  can  tell  each  other.  In  a  short  time 
the  father  can  tell  his  child  what  it  has  taken  him  a  life- 
time to  learn.  Children  of  ten  years  of  age  now  know 
much  more  about  some  things  than  men  used  to  know  a 
hundred  years  ago.  Some  persons  cannot  see  or  hear  or 
speak.  They  learn  with  great  difficulty,  but  finally  they 
can  be  taught  to  read  with  their  fingers  and  then  they 
learn  as  rapidly  as  others. 

243.  Need  of  a  healthy  body. — Thinking  is  work,  just 
as  running  or  any  other  action  of  the  cells  of  the  body  is 
work.     In  order  to  think,  the  cells  must  get  plenty  of  food 
and  oxygen.     The  cells  of  the  brain  are  the  first  to  suffer 
when  food  does  not  digest  or  the  air  is  foul.     A  headache 
and  dull  feelings  are  the  first  signs  that  something  is  wrong 
with  the  food  or  air.     Anything  that  makes  food  digest 
better,  or  that  causes  us  to  breathe  in  more  oxygen,  helps 
the  brain.     Plenty  of  out  of  door  exercise  is  a  great  help 
to  the  scholar.     The  best  student  generally  has  a  strong 
body. 

244.  Sleep.  —  The  brain   cells  work  and  become  tired 
like  any  other  part  of  the  body.     They  need  rest.     Some 


128  APPLIED   PHYSIOLOGY 

must  keep  acting  all  the  time.  The  spinal  cord  must  keep 
sending  orders  to  the  cells  to  eat  and  grow,  and  the  me- 
dulla must  send  orders  for  us  to  keep  breathing.  But  they 
send  an  order  and  rest  a  second,  and  then  send  another. 
Like  the  heart,  they  rest  half  the  time. 

When  the  thought  cells  rest,  we  do  not  know  anything, 
but  are  asleep.  During  sleep  they  regain  strength  and 
grow  like  a  resting  muscle. 

245.  Worry.  —  We  can  do  a  great  amount  of  hard  brain- 
work  if  we  can  only  sleep.     It  is  doubtful  if  any  one  can 
overwork  the  brain  if  he  gets  rest  in  sleep.     He  cannot 
help  sleeping  when  his   brain   gets  tired,   and  when  he 
wakes  he  will  be  ready  for  work  again.     But  sometimes 
a  person  is  troubled.     This  keeps  his  mind  in  action  just 
enough  to  prevent  his  resting.     Then  he  feels  tired,  even 
if  he  does  not  work,  for  he  gets  no  rest. 

246.  How   much   sleep  ?  —  A  child  needs  at  least  ten 
hours  of  sleep  each. day  up  to  the  age  of  twelve  years.     By 
the  time  he  is  eighteen,  he  needs  only  eight  hours.     By 
the  time  he  is  thirty,  six  or  seven  hours  of  good  sleep  will 
be  enough.    When  he  becomes  old  and  feeble,  he  will  need 
more  again. 

The  time  of  sleeping  is  of  less  importance  than  that  this 
time  should  be  regular.  A  short  nap  in  the  middle  of  the 
day  is  very  helpful. 

247.  Habit.  —  When  the  cells  of  the  brain  have  done  a 
thing  a  few  times,  they  want  to  do  it  again,  and  will  often 
act  without  our  knowledge.     So  we  can  form  a  habit  of 
doing  a  thing.      All  of  us  have  habits,  and  are  forming 
new  ones.     We  may  swear,  or  drink,  or  be  dishonest  once 
or  twice,  and  not  be  so  again.    But  if  the  temptation  comes 
again  we  shall  yield  more  easily  for  having  yielded  once, 
and  after  a  few  times  we  shall  yield  even  if  we  do  not 


THE   BRAIN 


129 


want  to.  Many  men  swear  when  they  do  not  know  they 
are  doing  it.  They  have  acquired  the  habit,  and  find  it 
very  hard  to  stop.  We  should  be  very  careful  how  we 
begin  to  do  a  wrong  thing,  for  no  matter  how  strong  a 
mind  we  have,  we  may  fall  into  the  habit  of  doing  the 
thing. 

248.  Good  habits.  —  We  can  also  form  good  habits.     If 
a  boy  is  brought  up  to  be  generous  and  to  speak  kindly, 
he  will  find  it  easy  to  do  so  all  his  life.     He  will  not  think 
that  giving  means  a  loss  to  himself,  but  he  will  find  as 
much  pleasure  in  the  joy  of  others  as  in  his  own  happiness. 
We  ought  to  form  habits  of  doing  good  deeds  and  saying 
kind  words.     Then  we  shall  be  of  benefit  to  all  around  us, 
and  shall  become  useful  and  noble  men  and  women. 

249.  Heredity.  —  Our  habits  affect  others  besides  our- 
selves and  our  neighbors.     They  may  become  transmitted 
to  our  children.     This  transmission  is  called  Jieredity.    The 
son  of  a  drunkard  will  be  likely  to  drink,  and  the  son  of  a 
thief  to  steal.     The  tendency  is  born  in  them.     To  get  rid 
of  it,  such  boys  must  be  taught  good  habits  from  their 
babyhood.      If   they  yield  once,  their  tendency  to  form 
the  bad  habits  of  their  fathers  will  be  stronger  than  their 
tendency  toward  the  good. 

250.  Nervousness.  —  A  man's  feelings  often  lead  him 
to  desire  things  which  his  thoughts  tell  him  are  wrong. 
Sometimes  his  feelings  are  made  very  unpleasant  by  little 
things  which  his  reason  tells  him  he  should  not  mind.     In 
all  persons  there  is  a  conflict  between  thought  and  feeling. 
Man  differs  from  the  lower  animals  in  that  he  puts  aside 
his  present  feelings  so  that  he  may  get  more  good  in  the 
future.     Reason  must  often  overrule  the  feelings,  to  deny 
them  a  pleasure  or  to  compel  them  to  endure  an  annoy- 
ance.    A  lack  of  self-control  is  nervousness. 

ov.  PHYSIOL.  (INTER.) — 9 


130  APPLIED   PHYSIOLOGY 

Nervous  persons  are  made  uncomfortable  by  slight 
noises,  or  by  little  pains,  or  by  being  denied  something 
that  they  want.  They  complain,  and  go  about  with  sad 
and  troubled  faces,  like  spoiled  children.  They  make 
more  fuss  over  a  slight  thing  than  they  would  over  the 
loss  of  a  dear  friend.  They  are  generally  afraid  that 
something  is  going  to  happen. 

Nervousness  is  to  a  great  extent  a  habit.  By  an  effort 
of  thought  any  one  can  overcome  nervousness.  It  is  the 
duty  of  every  one  to  do  this.  You  should  not  laugh  at  a 
nervous  person,  but  should  encourage  him  in  every  way  to 
become  as  brave  as  yourself. 

251.  Fear.  —  An  extreme  degree  of   nervousness  over 
any  one  thing  is  fear.     The  great  danger  in  fear  is  that  a 
person  may  not  think  of  what  he  is  about.     Then  instead 
of  escaping  from  danger  he  may  rush  into  it.     When  a 
crowd  is  in  danger,  as  in  a  burning  building,  all  are  liable 
to  rush  in  one  direction  and  to  trample  upon  each  other 
as  they  try  to  escape.     Then  a  cool  head  is  needed.     Do 
not  follow  the  crowd,  for  it  is  more  dangerous  than  the 
fire.     Remain  quietly  until  you  can  get  out  without  going 
in  the  crowd.     You  will  be  safer,  and  besides  you  will  do 
a  great  deal  towards  making  others  in  the  crowd  think 
of  what  they  are  doing. 

252.  Fire  drills  in  schools.  —  In  large  school  buildings, 
the  children  are  trained  to  drop  all  work  at  the  sound  of 
a  bell  and  to  march  quickly  from  the  building.     The  bell 
is  the  fire  alarm.     It  is  sounded  every  day  or  two  when 
the  children  are  not  expecting  it.      They  do  not  know 
whether  it  is  sounding  a  real  alarm  or  not.     When  a  fire 
really   occurs,    they  will    march   out   of   the   building   as 
orderly  as  in  the  drill.     The  drill  is  a  good  training  in 
bravery  and  self-possession. 


THE  BRAIN  13! 

253.  Dreams.  —  When  the  brain  is  asleep,  a  few  sets  of 
cells  may  recall  memories  so  vividly  that  they  seem  real. 
This  is  a  dream.     A  dream  is  not  an  indication  of  what 
is  to  take    place,   but   is    only  the    shadow  of  what   has 
already  been  done. 

254.  What  the  mind  is.  —  No  one  has  ever  been  able 
to  find  out  what  mind  is.     It  is  not  the  cells  of  the  brain, 
for  some  of  them  have  been  destroyed  in  men,  and  yet 
the  men  have  retained  perfect  minds.     It  seems  to  be  the 
soul,  or  spirit  of  men,  which  lives  in  the  cells  and  causes 
them  to  work  for  it.     We  believe  that  the  mind,  or  soul 
of  man,  lives  on  after  the  cells  in  which  it  dwells  are  dead. 

SUMMARY 

1.  The  medulla  oblongata  acts  for  the  head  as  the  spinal 

cord  does  for  the  body.     It  also  makes  and  sends 
out  the  orders  for  breathing. 

2.  The  cerebellum  gives  us  the  power  of  balancing  our- 

selves and  of  making  exact  movements. 

3.  The  cerebrum  is  made  of  nerve  cells  covering  a  central 

mass  of  nerve  threads. 

4.  The  mind  lives  in  the  nerve  cells  of  the  cerebrum,  and 

sends  its  orders  out  over  its  nerve  threads. 

5.  The  mind  feels  with  the  back  and  lower  parts  of  the 

sides  of  the  brain. 

6.  The  mind  sends  orders  for  movements  from  the  cells 

upon  the  top  of  the  sides  of  the  head. 

7.  The  mind  thinks  with  the  cells  behind  the  forehead. 

8.  By  means  of  the  nerve  threads,  the  mind  in  the  brain 

cells  can  talk  with  every  cell  of  the  body. 

9.  The  mind  is  the  spirit  of  man  which,  we  think,  lives 

on,  even  after  its  home,  the  body,  dies. 


CHAPTER   XIV 
NARCOTICS  AND  THE  NERVOUS  SYSTEM 

255.  How    alcohol    affects    the    mind.  —  Alcohol    may 
weaken  any  part  of  the  body,  but  this  is  of  minor  impor- 
tance compared  with  its   liability  to  ruin  the  mind  and 
character  of  men.     If  alcohol  is  swallowed,  but  little  can 
be  found  anywhere  in  the  body  at  the  end  of  an  hour. 
But  in  its  destruction  it  causes  the  albumin  of  the  body  to 
give  rise  to  poisonous  substances,  which  circulate  every- 
where among  the  cells.     These  poisons  are  probably  what 
affect  the  nervous  system  of  drinkers. 

256.  Alcohol  and  the  spinal  cord.  —  Because  alcohol  at 
first  makes  the  heart  beat  stronger,  it  drives  more  blood 
through  the  spinal  cord.     This  makes  the  nerve  cells  act 
more  quickly,  so  that  a  person  is  bright  and  active,  and 
feels  as  though  he  were  stronger  and  more  skillful  than 
usual.     He  is  ready  to  try  foolish  things  and  dangerous 
acts  in  order  to  show  his  skill.     He  notices  every  sound 
and  movement  and  jumps  at  slight  noises  which  do  not 
usually  annoy  him.     So  he  says  he  feels  nervous  and  he 
takes  more  drink  to  quiet  his  nervousness.      Finally  he 
gets  enough  alcohol  to  weaken  his  cells  so  that  they  cannot 
notice  anything,  or  send  proper  orders  to  feed  the  cells. 
Then  he  is  dead  drunk,  and  is  in  danger  of  his  life. 

257.  Alcohol  and  thought  — Alcohol  affects  the  brain  in 
much  the  same  way  that  it  does  the  spinal  cord.     At  first 
the  blood  flows  more  rapidly  and  makes  the  brain  more 
active.     A  drinker  is  full  of  thoughts  and  is  talkative,  but 

132 


NARCOTICS   AND   THE  NERVOUS   SYSTEM  133 

his  words  are  mostly  memories,  and  his  thought  cells  in  the 
forehead  do  very  little  new  work.  When  alcohol  begins  to- 
appropriate  oxygen  belonging  to  the  body,  the  brain  cells 
are  the  first  to  suffer.  Those  cells  of  the  brain  which  do 
the  highest  kind  of  work  suffer  first.  The  thought  cells  in 
the  forehead  are  the  first  'to  be  weakened.  The  highest 
kind  of  work  which  they  do  is  to  make  a  person  think  of 
the  feelings  of  others  before  his  own.  Drink  makes  a  man 
selfish  and  he  cares  less  for  others'  feelings  and  for  what 
they  think  of  him.  He  does  not  care  if  his  clothes  and 
face  are  dirty  and  if  he  is  disagreeable  to  others.  He  is 
easily  made  angry  and  often  wants  to  fight  over  small 
matters. 

The  next  actions  to  be  affected  are  thoughts  of  right  and 
wrong.  He  steals  without  reason,  and  may  commit  murder. 
Many  a  criminal  has  made  himself  half  drunk  so  that  he 
could  commit  the  crime  from  which  he  shrunk  when  sober. 

Finally,  all  the  cells  under  the  forehead  are  weakened 
and  the  man  cannot  think  at  all.  He  does  not  think  what 
might  be  the  result  of  his  acts,  but  is  as  likely  to  throw  a 
lighted  match  into  a  pile  of  paper  as  into  the  stove.  Many 
accidents  and  fires  are  due  to  the  lack  of  thought  of  drink- 
ing men. 

258.  Alcohol  and  motion.  —  A  person  thus  far  under  the 
influence  of  drink  is  often  very  amusing  in  his  talk.     He 
can  still  go  about  with  a  steady  gait,  but  he  cannot  be 
trusted  to  do  business.     If  he  stops  drinking,  the  effects 
will  pass  off  in  an  hour  or  two.     If  he  keeps  on  drinking, 
the  cells  which  cause  movements  of  the  muscles  are  next 
affected.     He  cannot  control  his  muscles,  but  walks  with 
an  unsteady  gait.     His  hands  tremble  and  he  talks  thick. 
He  is  now  drunk. 

259.  Alcohol   deadens   feeling.  —  Next,  the   cells  which 


134  APPLIED   PHYSIOLOGY 

receive  messages  of  feeling  are  weakened.  Then  the 
drunkard  does  not  feel  pain  so  keenly  as  he  should.  He 
gets  injured  without  knowing  it,  and  may  fall  and  freeze 
to  death  without  suffering.  Before  the  days  of  chloroform 
surgeons  used  to  make  their  patient  drunk  so  that  he  should 
not  feel  the  pain  of  the  operation. 

Because  alcohol  partly  deadens  feeling,  it  takes  away 
the  feeling  of  weariness,  and  the  drunkard  thinks  that, 
because  he  does  not  feel  tired,  the  whisky  has  made  him 
strong.  His  mind  is  dulled ;  he  has  not  the  sense  to  see 
that  he  really  has  lost  strength,  and  that  his  words  and  acts 
are  foolish.  He  judges  by  the  feeling  alone  and  keeps  on 
drinking,  though  each  drink  makes  him  still  weaker  and  a 
still  greater  fool.  But  the  next  day  the  effects  of  the 
alcohol  pass  off  and  he  feels  a  great  weakness  of  his  body 
and  brain,  and  needs  a  day  or  two  in  which  to  recover. 
Yet  in  a  little  while  there  comes  a  desire  to  drink  again. 
So  once  started,  the  habit  grows,  for  a  person's  good  sense 
is  taken  away,  and  he  is  too  weak  in  mind  to  see  the 
results. 

260.  Bad  companions.  —  Another  effect  upon  the  mind 
of  the  drinker  comes  from  his  being  with  other  men  in 
the  same  state  as  himself.     Their  low  stories  and  dirty 
language  and  quarrels  make  decent  men  ashamed.     No 
person  can  hear  them  without  being  shocked.     Yet  men 
become  like  those  with  whom  they  live,  and  so  drinkers 
learn  to  talk  and  think  alike. 

261.  Light  drinking.  —  A  weakness  of  mind  often  comes 
on,  even  if  a  drinker  never  gets  drunk,  and  it  is  often  in  a 
dangerous  form.     More  insanity  is  caused  by  drinking  than 
by  anything  else,  and  slow,  steady  drinking  causes  more  of 
it  than  getting  drunk  and  letting  drink  alone  between  times. 
Besides  those  who  are  made  insane,  many  are  so  weakened 


NARCOTICS  AND   THE   NERVOUS   SYSTEM  135 

in  mind  as  to  be  incapable  of  attending  to  business.  Many 
a  man  has  been  compelled  to  give  up  his  business  because 
he  has  been  a  steady  drinker  in  such  small  amounts  that 
even  his  friends  have  not  suspected  him.  His  trouble  is 
really  a  beginning  insanity. 

262.  Delirium    tremens.  —  There    is    a    disease    called 
delirium    tremens    which    any    drinker   may   get.       Hard 
drinking  alone  may  cause  it,  but  an  injuryrmay  bring  it  on 
in  any  drinker.     Delirium  tremens  is  a  disease  in  which 
the  victim  imagines  that  he  sees  all  manner  of  foul  animals 
coming  to  torment  him.     The  disease  is  one  of  the  most 
terrible  known,  and  is  very  dangerous  to  life. 

263.  Heredity.  —  Another  evil,   even  greater  than  the 
others,  is  that  the  effects  of  drinking  are  handed  down  to 
one's  children.     Nervousness  and  weakness  of  mind  and 
body  often  result.     But  worst  of  all,  children  often  grow  up 
with  a  desire  for  drinking.     Yet  no  person  has  the  right  to 
drink  because  his  father  drank.     It  is  within  the  power  of 
any  person  to  abstain  from  drink,  if  he  will. 

264.  Drinking   a   disease.  —  The    drinking    habit   is   a 
disease  of  the  mind.     While  a  person  should  be  punished 
for  the  crimes  he  commits  while  drunk,  he  should  not  be 
punished  for  drinking  any  more  than  an  insane  man  should 
be  punished  for  being  insane.     Neither  should  you  laugh 
at  the  drinking  habit  any  more  than  you  should  laugh  at 
any  other  kind  of  sickness.     The  friends  of  a  drinker  must 
be  the  same  comforters  and  helpers  that  they  would  be  if 
he  were  sick  in  any  other  way.     He  must  be  led  to  use  his 
will  in  putting  away  the  habit.     He  should  be  made  to 
know  that  he  is  sick  and  unfit  for  work.     When  people 
cease  to  be  amused  at  drunkards  and  learn  to  treat  them 
as  sick  in  mind,  drinking  will  become  unpopular,  for  men 
do  not  like  to  be  called  sick.     Fifty  years  ago  men  were 


136  APPLIED   PHYSIOLOGY 

ashamed  to  say  that  they  did  not  drink ;  now  men  are 
getting  to  be  ashamed  of  drinking. 

265.  Waste  from  alcohol.  —  In  the  United  States  alone 
one  and  a  half  billions  of  dollars  are  paid  for  strong  drink 
each  year.  The  drink  is  made  from  good  fruit  and  grain 
which  can  otherwise  be  used  as  food  for  man  or  animals. 
Bread  costs  the  people  less  than  half  as  much  as  strong 
drink.  For  every  dollar  spent  for  the  support  of  churches 
fifteen  are  spent  for  strong  drink.  To  pay  the  drink  bill 
each  year  would  take  ten  times  more  gold  and  silver  than 
is  mined.  The  price  of  two  or  three  drinks,  if  it  were  put 
in  a  savings  bank  each  day  would  amount  to  enough  in  ten 
years  to  pay  for  a  comfortable  home. 

The  loss  to  the  drinker  is  only  a  small  part  of  the  whole 
loss.  Because  of  sickness  and  loss  of  strength  due  to 
strong  drink  the  men  who  hire  drinkers  do  not  get  the  full 
value  for  their  money.  In  Great  Britain  it  is  calculated 
that  the  amount  of  labor  lost  by  drink  would  amount  to  at 
least  two  hours  every  day  for  every  workingman.  The 
loss  is  made  much  greater  if  we  count  the  accidents  to 
property,  health,  and  even  to  life  caused  by  persons  under 
the  influence  of  strong  drink. 

We  must  add  to  this  estimate  the  amount  spent  on  jails 
and  insane  asylums,  for  over  one  half  of  all  crime  and  in- 
sanity is  directly  produced  by  strong  drink.  We  must  also 
add  the  loss  of  great  numbers  of  strong  workers  who  once 
filled  high  positions  but  have  lost  them  because  of  strong 
drink.  We  must  also  consider  the  loss  of  a  far  greater 
number  of  young  men  who  would  have  risen  to  be  re- 
spected citizens  if  it  were  not  for  strong  drink. 

To  all  this  money  waste  we  must  add  the  amount  of 
suffering  and  want  which  the  drinkers'  families  at  home 
must  bear.  We  must  also  remember  the  number  of  chil- 


NARCOTICS   AND   THE  NERVOUS   SYSTEM  137 

dren  who  fall  into  bad  habits  from  the  lack  of  the  good 
example  and  restraint  of  their  intemperate  parents.  The 
money  loss  of  strong  drink  can  be  restored,  but  the  suffer- 
ing can  never  be  repaid.  When  all  has  been  reckoned,  it 
will  be  found  that  strong  drink  is  the  cause  of  more  waste 
and  evil  than  any  other  known  thing.  It  affects  every  one 
in  the  land,  therefore  it  is  right  to  make  laws  which  shall 
control  the  sale  of  liquor,  or  even  stop  its  sale  altogether. 

266.  Bitters.  —  There  is  a  form  of  alcohol  which  many 
use  and  do  not  know  it.     Strengthening  bitters,  Jamaica 
ginger,  and  many  tonics  are  simply  strong  alcohol  with 
flavors  added.     They  produce  the  same  stimulating  effects 
as  whisky,  and  can  easily  make  a  person  drunk.     Their 
effects  are  due  to  their  alcohol.     Some  persons  even  have 
a  habit  of  their  use  just  as  men  form  a  habit  of  using  other 
kinds  of  alcoholic  drinks. 

267.  Drug  habits.  —  Opium  and  chloral  are  sometimes 
used  to  quiet  the  brain  and  to  produce  sleep.     They  are 
dangerous  drugs,  for  after  their  effects  have  passed  off,  the 
brain  feels  worse  than  ever,  and  nothing  but  the  same  drug 
will  make  it  feel  well  again.     So  persons  form  habits  of 
their  use.    They  quickly  weaken  the  whole  body,  and  affect 
the  brain  more  than  any  other  part.     Those  who  use  the 
drug  seldom  live  more  than  a  year  or  two.     Many  other 
drugs  will  also  lead  to  slavish  habits  of  taking  them,  but 
opium  and  chloral  are  the  most  common  ones. 

268.  Headache  powders.  —  There  are  a  number  of  simi- 
lar drugs  made  from  coal  tar  which  are  used  to  relieve 
headaches.     Phenacetine  is  the  most  common  one.     Under 
a  doctor's  direction  they  are  valuable  remedies ;  but  many 
use  them  on  their  own  responsibility,  and  finally  find  that 
they  do  not  feel  well  without  the  drug.     All  these  drugs 
weaken  the  heart  and  may  produce  violent  poisoning. 


138  APPLIED   PHYSIOLOGY 

269.  Tea  and  coffee. — Many  persons  who  use  tea  and 
coffee  do  not  feel  well  without  them.     They  stimulate  the 
brain  to  greater  exertion ;  but  when  their  use  is  stopped 
the  brain  feels  its  weariness.     Then  another  cup  is  needed, 
and  so  a  habit  of  their  use  is  formed.     They  often  produce 
headaches  and  disordered  stomachs,  and  so  their  habitual 
use  weakens  the  whole  body,  including  the  brain.     They 
often  produce  nervousness  and  sleeplessness.     They  should 
be  regarded  as  drugs  and  not  as  food.      Young  people 
especially  are  easily  harmed  by  their  use. 

270.  Tobacco.  —  Men  use  tobacco  to  quiet  their  brains. 
When  they  are  alone  they  use  it  for  company,  to  keep 
from  thinking,  but  when  they  are  with  others  they  use  it 
because  the  rest  do.     On  the  other  hand,  some  men  use 
tobacco  to  make  themselves  think.     Now,   it  cannot  do 
both  of  these  things.     In  reality,  it  does  not  increase  the 
power  of  the  brain,  for  it  is  a  poison.     Some  men  seem  to 
stand  tobacco  with  but  little  harm,  but  no  one  can  use  it 
and  have  the  best  brain. 

271.  Tobacco    and    drink.  —  Some    people    think    that 
tobacco  quiets  a  person's  brain  when  he  has  been  drink- 
ing.    This  is  because  tobacco  lessens  the  overaction  of 
the  brain  which  alcohol  at  first  produces.     On  the  other 
hand,  a  little  alcohol  seems  to  make  the  tobacco  user  feel 
stronger,  and  to  relieve  his  thirst  caused  by  tobacco.     So 
tobacco   and  alcohol  naturally  go  together.      A  drinker 
almost  always  uses  tobacco,  for  its  poison  seems  to  relieve 
the  poison  of  alcohol ;  but  it  only  seems  to  do  so,  for  in 
reality  it  makes  a  person  want  more  drink. 

272.  Waste  from  tobacco.  —  Like  strong  drink,  the  use 
of  tobacco  is  extremely  wasteful.     In  the  United  States 
half  as   much  is   spent  for  tobacco  as   for  strong  drink. 
The  land  upon  which  it  is  grown  is  not  only  prevented 


NARCOTICS   AND  THE  NERVOUS   SYSTEM  139 

from  bearing  useful  crops,  but  is  also  soon  worn  out  so  that 
it  will  not  produce  any  kind  of  a  crop  without  large  ex- 
penses for  fertilizers.  Many  fires  are  caused  by  the  care- 
less use  of  matches  in  lighting  pipes  and  cigars.  While 
men  often  take  strong  drink  because  they  may  think  it 
may  do  them  good,  they  chew  and  smoke  only  for  their 
pleasure.  This  tends  to  careless  and  wasteful  habits  of 
living.  A  man  is  seldom  so  poor  but  that  he  will  have  a 
smoke,  even  while  his  family  may  be  compelled  to  live  on 
charity. 

273.  Chewing  gum.  —  Chewing  gum  is  made  from  pitch, 
paraffin,  and  other  thick  and  sticky  substances  which  do 
not  dissolve  in  water.     The  gum  itself  has  no  effect,  for  it 
is  not  dissolved  and  swallowed ;  but  the  act  of  chewing  it 
causes  a  free  flow  of  saliva  when  it  is  not  needed,  and 
so  there  will  be  less  formed  during  meals  when  it  is  neces- 
sary for  digestion.     If  gum  from  a  dirty  pocket  is  given  to 
another  person  it  may  carry  disease  germs.     Beyond  this, 
chewing  gum  has  little  or  no  effect  on  the  body.     But  its 
use  is  uncleanly  and  is  unpleasant  to  others.     It  seems 
much  like  chewing  tobacco,  and  refined  persons  avoid  even 
the  appearance  of  evil.     Its  use  may  encourage  boys  to 
chew  tobacco  later  in  life. 

274.  Alcohol  in  cooking.  —  In  raising  bread  by  means  of 
yeast,  alcohol  is  always  formed,  but  the  heat  of  the  baking 
drives  it  off,  so  that  all  trace  of  it  is  lost.     In  preparing 
puddings,  pies,  and  cakes,  brandy  or  wine  is  often  added 
to  give  them  flavor.     If  they  are   cooked   afterward,  the 
heat  will  drive  off  the  alcohol  and  so  render  the  dessert 
harmless.     If  it  is  not  cooked  afterward  the  alcohol  re- 
mains in  the  dessert  and  may  do  as  much  harm  as  if  it 
were  taken  in  the  form  of  the  original  brandy. 

Even  when  all  the  alcohol  is  driven  off  from  a  dessert, 


I4O  APPLIED   PHYSIOLOGY 

the  flavor  of  the  brandy  or  wine  remains  behind  and  may 
teach  persons  to  like  the  taste  of  the  liquor  itself.  Chil- 
dren who  eat  the  dessert  may  grow  up  to  like  the  taste  of 
the  liquor  even  though  they  never  drank  a  drop  of  the 
liquor  itself.  In  this  way  desserts  flavored  with  liquor 
may  do  much  harm. 

In  bread,  the  alcohol  has  no  special  flavor,  and  so  we 
can  eat  bread  without  danger  of  learning  to  like  the  taste 
of  liquors. 

275.  Alcohol  in  confectionery.  —  Candies  sometimes  con- 
tain brandy  or  whisky  which  is  put  in  for  their  flavors. 
One  form  of  candy  has  a  hollow  center  filled  with  brandy. 
Children  who  buy  the  candy  learn  to  like  the  taste  of  the 
liquor.     The  sale  of  brandy  or  of  any  other  form  of  liquor 
in  that  way  is  a  breaking  of  the  law,  for  the  candies  contain 
more  brandy  than  many  strong  drinks. 

276.  Homemade  wines.  —  It  must  not  be  supposed  that 
a  wine  is  harmless  because  it  has  been  made  at  home  from 
good  grapes  or  blackberries,  without  adding  any  alcohol  at 
all.     The  alcohol  in  wine  does  not  need  to  be  put  there,  for 
the  fruit  juice  ferments  and  forms  it.     If  any  liquor  fer- 
ments at  all  it  contains  alcohol,  and  so  is  a  strong  drink. 
Homemade  wines  are  often  stronger  in  alcohol  than  many 
bought  wines. 

277.  Strong  drink  as  a  medicine.  —  It  is  a  custom  to  give 
some  form  of  alcoholic  stimulant  whenever  a  person  meets 
with  an  accident,  or  is  seized  with  a  sudden  illness.     It  is 
doubtful  whether  it  ever  does  much  good  at  such  a  time. 
On  the  other  hand,  it  may  be  the  very  thing  which  ought 
not  to  be  given.     For  instance,  if  a  person  is  bleeding,  it 
may  cause  the  blood  vessels  to  become  larger  and  so  lead 
to  a  greater  loss  of  blood. 

Taking  strong  drink  to  break  up  a  cold  is  liable  to  bring 


NARCOTICS  AND   THE  NERVOUS   SYSTEM  141 

on  a  greater  cold  by  causing  more  blood  to  flow  near  the 
surface  of  the  skin,  where  its  heat  will  readily  be  lost. 

The  greatest  danger  of  all  in  the  household  use  of  strong 
drink  as  a  medicine  is  that  children  may  grow  up  with  the 
idea  that  it  is  a  good  thing  to  use  under  almost  all  circum- 
stances. Thus  it  tends  to  encourage  them  in  its  use.  No 
one  can  use  an  alcoholic  drink  with  safety  even  as  a  medi- 
cine unless  he  is  directed  by  a  physician. 

278.  Treating.  —  A   harmful   practice    connected   with 
drinking  is  the  custom  of  treating.     Many  a  man  would 
not  drink  if  he  were  not  invited  by  a  friend.     Then  he  does 
not  dare  to  refuse  either  from  fear  of  offending  his  friend 
or^of  being  laughed  at.     He  may  be  led  to  take  several 
drinks  against  his  will. 

In  Europe  treating  is  seldom  done.  It  would  be  much 
better  if  Americans  would  not  induce  their  friends  to  drink. 
The  custom  and  habit  of  treating  is  not  confined  to  men 
and  women,  but  children  learn  it  in  treating  each  other  to 
candy.  It  is  well  to  be  generous,  but  it  would  be  well  to 
do  a  person  good  instead  of  harm  by  your  generosity. 

279.  Ether   and   chloroform.  —  Alcohol  is  used  in  the 
manufacture  of  ether  and  chloroform.     These  two  drugs 
are  used  to  produce  a  deep  sleep  in  which  operations  can 
be  done  on  the  body  without  giving  pain.     As  soon  as  they 
are  breathed  into  the  lungs  they  begin  to  stupefy  a  person, 
but  at  first  they  also  cause  him  to  cry  out  and  to  toss  him- 
self about  like  a  drunken  man.     In  about  five  minutes  he 
is  in  a  deep  sleep  and  can  be  kept  so  for  an  hour  or  two 
while  the  operation  is  being  done. 

When  the  ether  or  chloroform  is  stopped  a  person  slowly 
awakens  and  talks  in  a  wandering  way  for  some  time.  In 
about  half  an  hour  he  becomes  wide  awake  again.  The 
condition  of  a  man  who  is  deeply  under  the  influence  of 


142  APPLIED   PHYSIOLOGY 

strong  drink  resembles  the  condition  of  one  who  has  taken 
chloroform.  But  the  effects  of  chloroform  soon  pass  off, 
while  alcohol  acts  slowly,  so  that  a  person  may  die  before 
he  can  recover  his  senses. 

SUMMARY 

1.  Alcohol  interferes  with  the  action  of  the  nerves  and, 

spinal  cord. 

2.  Alcohol  overcomes  the  brain,  first  attacking  its  highest 

acts. 

3.  When  a  man  is  coming  under  the  influence  of  alcohol, 

he  first  becomes  selfish,  and  then  careless.  Then  he 
cannot  control  his  movements,  and  next  he  cannot 
feel.  Finally  he  is  dead  drunk,  and  may  die. 

4.  Continuous  drinking,  even  if  light,  may  overcome  the 

mind  so  that  it  becomes  insane. 

5.  In  some  cases  alcohol  causes  horrible  dreams  called 

delirium  tremens. 

6.  A  drinker  may  transmit  his  mental  weakness  to  his 

children. 

7.  Drinking  is  a  disease  of  the  mind. 

8.  Tobacco  weakens  the  brain,  as  it  does  all  other  parts 

of  the  body. 


CHAPTER   XV 

THE   SENSES 

A  MAN  knows  what  is  going  on  around  him  in  five  ways. 
He  can  feel,  see,  hear,  smell,  and  taste. 

280.  Feeling.  —  Nerves  of  feeling  go  to  every  part  of 
the  body.     Most  of  them  end  in  the  skin.     When  any- 
thing touches  them,  they  carry  a  message  about  it  to  the 
upper  part  of  the  brain.      These  messages  are  of  three 
kinds :  touch,  pain,  and  temperature. 

281.  Touch.  —  When  anything  touches  the   body,  but 
does  not  harm  it,  the  nerves  carry  a  message  simply  of 
touch.     By  means  of  this  message  the  brain  tells  whether 
the  substance  touched  is    hard  or    smooth,  or  round  or 
pointed,  or  has  other  qualities. 

The  tip  of  the  tongue  and  the  ends  of  the  fingers  are 
very  sensitive.  The  fingers  can  feel  two  pins  distinctly 
if  they  are  only  one  twelfth  of  an  inch  apart,  while  the 
back  feels  them  as  one  if  they  are  two  inches  apart.  We 
use  the  tips  of  the  fingers  if  we  wish  to  feel  with  accuracy. 

By  education,  the  sense  of  touch  can  be  made  very  deli- 
cate. Blind  persons  learn  to  do  things  by  touch  almost  as 
well  as  we  do  by  sight. 

282.  Pain.  —  If  anything  touching  the  cells  is  harming 
them,  we  no  longer  feel  a  touch,  but  only  a  pain.     Then 
we  do  not  think  whether  the  substance  is  hard,  or  smooth, 
but  only  that  it  is  doing  us  harm.     So  pain  tells  us  if  any- 
thing is  harming  the  body.     A  toothache  shows  that  a 


144 


APPLIED   PHYSIOLOGY 


tooth  is  decaying  and  needs  filling.  If  we  could  not  feel 
pain,  an  arm  or  a  leg  might  be  burned  or  cut  without  our 
knowing  it. 

283.  Temperature.  —  We  feel  heat  or  cold  by  special 
nerves  in  the  skin.  Draw  a  cold  pencil  point  slowly  over 
the  face.  You  feel  its  touch  as  it  moves  over  your  face, 
but  at  a  few  points  you  feel  only  a  coldness.  These  points 
are  scattered  over  the  skin  so  close  together  that  the  whole 
skin  seems  to  feel  the  sensation.  Whenever  heat  or  cold 
is  great  enough  to  harm  the  body,  we  feel  only  a  pain. 


a  bone  of  the  orbit. 
b  muscle  which  moves 

the  eyeball. 
c  sclerotic  coat. 
d  choroid  coat. 


The  human  eye. 

e  retina. 
/  eyelid. 
g  ins. 
h    lens. 


t  cornea. 

j  muscle  which  changes 

the    shape    of    the 

lens. 
k  optic  nerve. 


284.  The  eye.  —  The  eye  is  a  round  white  globe  filled 
with  a  clear  fluid.  In  its  front  is  a  clear  round  window, 
behind  which  is  a  muscular  curtain  called  the  iris.  The 
iris  is  blue  or  brown,  and  gives  the  color  to  the  eye.  In  its 
center  is  a  round  black  hole  called  the  pupil.  The  pupil 


THE   SENSES  145 

can  become  larger  or  smaller  so  as  to  regulate  the  amount 
of  light  which  enters  the  eye.  In  a  bright  light  it  becomes 
small  and  shuts  out  some  of  the  rays.  In  a  dim  light  it 
becomes  large,  and  admits  all  the  light  it  can.  Notice  the 
pupil  of  a  cat's  eye.  In  the  middle  of  the  day  it  is  a 
narrow  slit,  but  in  the  evening  it  is  almost  round,  and 
admits  more  light  than  the  pupil  of  a  man's  eye.  A  cat 
can  see  well  when  it  is  so  dark  that  we  cannot  see  at  all. 

Behind  the  pupil  is  a  clear  body,  shaped  like  two  saucers 
put  together  by  their  edges,  or  like  a  magnifying  glass. 
It  is  called  a  lens.  A  magnifying  glass  brings  rays  of 
light  together  into  one  bright  spot.  The  lens  of  the  eye 
brings  together  the  rays  from  an  object,  and  they  form  a 
picture  upon  the  nerves  in  the  back  part  of  the  eyeball, 
like  a  picture  in  a  photographer's  camera.  The  nerves 
carry  the  impression  of  the  picture  to  the  back  part  of  the 
brain  and  so  produce  sight. 

285.  Movements  of  the  eyes.  —  The  eyes  can  be  turned 
in   any   direction  we  wish  by  means  of  muscles.     Some- 
times the  eyes  will  not  turn  together,  but  while  one  looks 
at  one  object,  the  other  looks  somewhere  else,  making  the 
person  cross-eyed.     A  cross-eyed  person  usually  sees  with 
only  one  eye.     If  the  eye  is  treated  before  a  child  has 
grown,  it  can  be  cured. 

286.  Coverings  of  the  eyes.  —  The  eyeball  lies  upon  a 
bed  of  fat  in  a  bony  case.     It  is  covered  in  front  by  two 
lids  of  flesh.     These  can  be  shut  so  as  to  protect  the  eye 
from   dust  or  injuries.     Whenever   anything   is  about  to 
enter  the  eye,  it  causes  the  lids  to  close  so  as  to  shut  it 
out.     We  cannot  help  winking  when  something  is  about 
to  strike  the  eye.     When  we  are  sleepy,  we  cannot  keep 
the  lids  from  falling  together. 

Hairs   grow  from   the  edges    of   the  lids.      They  curl 
ov.  PHYSIOL.  (INTER.)  —  10 


146  APPLIED   PHYSIOLOGY 

away  from  the  eyeball  so  as  to  catch  whatever  might  fall 
against  the  eye. 

287.  Dirt  under  the  lids.  — The  front  side  of  the  eyeball 
and  the  lining  of  the  lids  are  very  tender.     If  only  a  little 
dirt  gets  under  the  eyelid,  it  gives  great  pain.     Then  the 
eye  should  be  kept  still  until  the  dirt  can  be  taken  out. 
Rubbing  grinds  the  dirt  into  the  eye  and  makes  it  sore. 
Never  rub  the  eye  when  you  think  it  has  something  in  it. 
Lift  the  lid  by  the  eyelashes  and  the  tears  will  usually 
wash  the  dirt  away.     If  they  do  not,  let  some  one  raise 
the  lid  and  pick  out  the  dirt  with  a  soft  handkerchief. 

288.  Tears. — The  eyeball   is  moistened  with  a  saltish 
liquid  called  tears.    They  are  produced  by  a  gland  situated 
just  above  and  to  the  outside  of  the  eye.     They  run  over 
the.  surface  and  down  a  small  tube,  and  into  the   nose. 
Winking  rubs  the  liquid  over  the  whole  surface  of  the  eye 
so  as  to  wash  away  dust.     When  you  cry,  the  tears  flow 
faster  than  the  tube  can  carry  them  into  the  nose.     Then 
some  overflow  upon  the  cheeks. 

289.  Care  of  the  eyes.  —  Your  eyes  ought  never  to  ache 
from  use.     If  they  do  ache,  you  are  straining  them  and 
may  do  them  great  harm.     You  can  use  your  eyes  safely 
until  they  begin  to  ache.     At  the  first  signs  of  discomfort, 
you  should  stop  work  and  give  them  a  rest. 

A  bright  light  in  front  of  the  eyes  is  the  most  common 
cause  of  eye  strain.  At  night  there  should  always  be  a 
shade  over  the  lamp,  or  else  you  should  wear  a  shade  over 
your  eyes.  A  cap  will  do  for  a  shade  if  you  cannot  get 
anything  else. 

The  light  should  come  from  one  side  or  over  your 
shoulder.  Then  it  will  not  shine  into  your  eyes.  You 
should  never  try  to  look  at  the  sun.  You  should  never  try 
to  read  by  a  dim  or  unsteady  light. 


THE   SENSES  147 

In  a  carriage  or  a  railway  car,  your  paper  will  shake, 
and  you  must  be  continually  moving  your  eyes  to  see.  This 
makes  the  eyes  ache.  You  ought  not  to  try  to  read  under 
these  conditions. 

When  you  read  while  lying  down,  you  turn  your  eyes 
in  the  direction  of  your  feet,  which  is  very  tiresome. 

290.  Nearsightedness.  —  In  order  to  see  objects  clearly, 
some  persons  must  hold  them  close  to  their  eyes.     This 
is   called   nearsightedness.      Nearsighted    persons    should 
always  wear  spectacles.     This  will  enable  them  to  see  as 
well  as  any  one. 

291.  Farsightedness.  —  As  persons  grow  old,  they  can- 
not see  near  by  so  well  as  afar  off.     This  is  called  far- 
sightedness.    By  wearing  spectacles,  they  can  see  as  well 
as  ever. 

292.  Alcohol  and  the  eyes.  —  Alcohol  causes  the  eyes 
to  look  red,  and  may  make  them  sore.     In  some  cases 
it  causes  the  nerves  of  the  eye  to  waste  away.     Then  the 
eye  will  be  blind,  although  it  will  appear  well. 

In  drunken  persons  the  muscles  of  the  eyes,  like  the 
muscles  of  the  legs,  do  not  act  rightly.  They  often  turn 
the  eyes  in  different  directions.  Then  the  person  will  be 
cross-eyed,  and  every  object  will  seem  double. 

Tobacco,  in  some  cases,  causes  the  nerve  of  sight  to  waste 
away.  Tobacco  smoke  makes  the  eyes  smart  so  that  the 
tears  flow. 

293.  The   ears.  —  We   hear   with   our   ears.     Sound   is 
made  by  waves  of  air  which  beat  upon  special  nerves. 
The  ear  is  a  cavity,  hollowed  out  of  a  very  hard   bone, 
and  is  divided  into  three  parts. 

294.  The  outer  ear.  —  The  outer  ear,  which  we  see,  is 
not  needed,  but  it  does  some  good  in  catching  the  waves 
of  sound  and  throwing  them  into  the  tube  in  its  center. 


,48 


APPLIED    PHYSIOLOGY 


This  tube  enters  the  skull.     The  tube  and  the  ear  which 
we  see  are  called  the  outer  ear. 

295.  The  middle  ear.  —  At  the  end  of  the  tube  of  the 
outer  ear  a  thin  membrane  is  stretched  like  the  head  of 
a  drum.  Beyond  it  is  a  hollow  cavity  which  is  like  a 
drum,  and  is  called  the  middle  ear.  Air  waves  strike 


Diagram  of  the  ear. 

a  outer  air  passage.  f  semicircular  canals. 

b  membrana  tympani.  g  vestibule  of  inner  ear. 

c  malleus,  or  hammer  bone.  h  cochlea. 

d  incus,  or  anvil  bone.  i    Eustachian  tube. 

e  stapes,  or  stirrup  bone.  j   tympanum,  or  middle  ear. 

the  drumhead  and  cause  it  to  move  rapidly  back  and 
forth,  just  as  a  drumhead  moves  when  it  is  struck.  A 
•chain  of  three  little  bones  stretches  across  the  drum  and 
carries  the  movements  of  the  drumhead  to  a  third  cavity 
called  the  inner  ear. 

296.  The  inner  ear.  —  The  inner  ear  is  made  up  of  coiled 
tubes.  It  is  filled  with  a  clear  liquid  into  which  the  nerves 
of  hearing  project.  The  movements  of  the  little  bones 
produce  waves  in  the  liquid,  which  beat  against  the  nerves. 
Our  brains  feel  the  waves  as  a  sound.  The  outer  ear  con- 
ducts the  sound  to  the  middle  ear.  The  middle  ear  acts 


THE   SENSES  149 

Mke  a  sounding  box  to  make  it  plainer  and  more  distinct. 
The  inner  ear  is  the  real  ear.  Some  animals,  like  fish, 
have  only  an  inner  ear. 

297.  The   Eustachian   tube.  —  The  middle   ear  is  filled 
with  air.     From  it  a  tube,  called  the  Eustachian  tube,  ex- 
tends to  the  back  part  of  the  nose.     When  you  blow  your 
nose  hard,  you  can  force  air  up  the  tube.      This  makes 
your  ears  feel  full,  and  you  become  partly  deaf.     When 
you  have  a  cold,  the  tube  may  become  stopped,  and  then 
your  ear  rings  and  feels  as  if  you  had  blown  air  up  the 
tube.     If  it  stays  stopped,  you  may  become  deaf. 

Sometimes  a  cold  in  the  throat  extends  up  the  tube  and 
into  the  middle  ear.  Then  you  have  an  earache,  and  per- 
haps your  ear  may  discharge  matter  like  that  from  your 
throat.  Throat  trouble  is  the  most  common  cause  of  ear- 
ache and  deafness  in  children.  If  a  child  breathes  through 
his  mouth  or  has  too  large  tonsils  or  anything  growing 
in  the  back  part  of  his  nose,  he  is  very  liable  to  have  ear- 
ache or  deafness.  So  it  is  very  important  for  you  to  have 
your  nose  and  throat  in  good  order  if  you  would  have  good 
hearing.  Scarlet  fever  often  causes  deafness,  because  the 
inflammation  of  the  throat  extends  up  the  tube  to  the  ears. 

298.  Dull   children.  —  Sometimes    children    get    throat 
trouble  and  earache  before  they  can   talk.      Then  they 
grow  up  slightly  deaf,  but  neither  they,  nor  their  parents, 
nor  their  teachers  know  it.     Such  children  cannot  hear 
well  when  spoken  to,  and  so  seem  to  be  dull  and  careless. 
Often  they  are  punished  for  not  attending  to  their  work. 
This  is  very  unjust  to  the  child.     Every  child  that  seems 
inattentive  or  slow  in   obeying  should    have  his  hearing 
tested.     Hold  a  watch  to  his  ear  and  see  if  he  can  hear 
it  as  far  away  as  you  can. 

299.  Care  of  the  ears.  —  Boxing  the  ears  may  burst  the 


I5O  APPLIED   PHYSIOLOGY 

drumhead,  just  as  hitting  a  drum  too  hard  may  spoil  it. 
This  may  cause  deafness.  You  should  never  strike  a  per- 
son upon  the  ears  in  play.  A  very  loud  noise  may  also 
burst  the  ear  drum,  or  at  least  cause  pain  and  deafness. 
You  should  stop  your  ears  when  you  expect  a  loud  noise. 
Men  who  shoot  cannon  often  have  to  put  cotton  into  their 
ears  before  they  fire. 

Cold  water  in  the  ear  may  cause  an  earache.  When 
you  get  water  in  your  ear  while  you  are  in  swimming,  turn 
your  head  to  one  side  and  shake  it  so  that  the  water  will 
run  out. 

Do  not  put  anything  into  your  ear.  It  is  very  hard  to 
get  a  bean  or  a  stone  out  again.  Cotton  in  the  ear  makes 
the  ear  tender  and  causes  more  colds  than  it  prevents. 

If  the  ears  run  with  matter,  wash  them  out  with  clean 
water  and  borax.  Do  not  plug  them  up  with  cotton  or 
anything  else,  for  that  will  keep  the  matter  in. 

300.  Ear  wax.  —  The  outer  tube  of  the  ear  produces  a 
kind  of  bitter  wax.     This  keeps  insects  from  crawling  into 
the  ear.     Sometimes  it  collects  into  a  mass.     By  trying  to 
get  it  out  you  may  force  it  farther  into  the  ear  and  against 
the  drumhead.     Then  you  will  become  partly  deaf. 

You  should  not  pick  your  ears,  for  you  may  hurt  the 
drumhead.  The  wax  naturally  grows  outward,  and  so  does 
not  collect  in  the  ear  if  it  is  left  alone. 

301.  The  nose.  —  We  smell  with  the  nose.     In  the  upper 
part  of  the  nose  fine  nerves  are  spread  out  beneath  the 
epithelium.     When  a  vapor  in  the  air  soaks  through  the 
wet  sides  of  the  nose,  it  touches  the  nerves  and  produces 
the  sense  of  smell. 

In  order  to  have  a  smell,  a  substance  must  become  a 
vapor.  So  those  substances  which  cannot  become  a  vapor 
have  no  smell.  A  very  small  amount  of  a  substance  in  the 


THE   SENSES 


air  will  excite  the  sense  of  smell.  A  tiny  grain  of  musk 
will  continue  to  give  out  vapor  and  produce  a  smell  for 
years,  and  yet  will  not  seem  to  diminish  at  all  in  size. 


The  outer  wall  of  the  nose. 

a  the  nerve  of  smell  at  the  base  of  the  d  curved  curtains  of  bone. 

brain.  e  opening  of  the  Eustachian  tube. 

b  air  spaces  in  the  skull  bones.  /  soft  palate. 

c  branches  of  the  nerve  of  smell.  g  upper  jawbone. 

302.  Use  of  smell.  —  Spoiled  food  and  bad  air  each  give 
off  a  bad  smell,  while  good  food  and  good  air  always  smell 
good.     The  sense  of  smell  guards  us  against  bad  air  and 
bad  food. 

When  we  have  a  cold  in  the  nose  we  cannot  smell.  We 
must  keep  from  taking  cold  if  we  would  have  a  good  sense 
of  smell. 

Alcohol  and  tobacco  are  irritating  to  the  nose,  and  spoil 
the  sense  of  smell.  Then  the  great  safeguard  against  bad 
air  and  bad  food  is  taken  away. 

303.  Taste.  —  The  nerves  of  taste  are  situated  mostly 


152  APPLIED    PHYSIOLOGY 

upon  the  tongue.  A  substance  dissolves  in  the  saliva  and 
soaks  through  the  epithelium  of  the  tongue,  and  touching 
the  nerves  produces  the  sense  of  taste.  A  substance  that 
will  not  dissolve  in  water  has  no  taste. 

The  sense  of  taste  tells  us  what  food  is  good  for  us. 
Unwholesome  or  spoiled  food  generally  has  a  bad  taste. 
We  can  learn  to  like  some  things  that  are  not  good  for  us. 
Tobacco  does  not  taste  good  at  first,  but  men  learn  to  like 
it.  We  never  tire  of  the  taste  of  wholesome  food,  but 
when  we  get  too  much  sweets  or  candy,  their  taste  makes 
us  sick.  Even  if  a  thing  tastes  good  at  first,  its  taste  may 
afterward  show  it  to  be  unwholesome. 

We  should  not  injure  the  nerves  of  taste  by  using 
tobacco  or  alcohol.  Even  pepper  and  spices  may  injure 
the  taste  so  that  we  cannot  tell  when  food  is  bad. 

Sometimes  the  senses  of  smell  and  taste  blend  together. 
If  the  sense  of  smell  is  lessened,  as  by  a  cold  in  the  head, 
coffee  does  not  taste  so  good  as  it  should.  If  the  nose  is 
stopped,  persons  can  scarcely  recognize  the  taste  of  onions. 

SUMMARY 

1.  Anything  touching  the  nerves  produces  a  feeling  of 

touch,  or  of  pain  or  of  temperature. 

2.  Touch  tells  us  about  the  shape,  hardness,  smoothness, 

and  similar  qualities  of  objects. 

3.  Pain  tells  us  that  something  is  harming  the  body. 

4.  Light  passes  into  the  eyeball  and  forms  a  picture  upon 

nerves,  and  thus  produces  the  sense  of  sight. 

5.  Muscles  turn  the  eye  about,  lids  protect  it,  and  tears 

wash  away  dust  from  it. 

6.  Too  bright  a  light  harms  the  eyes. 

7.  Air  waves  pass  into  the  tube  of  the  outer  ear,  and  are 

carried  across  the  middle  ear  by  a  chain  of  bones  to 


THE  SENSES  153 

nerves,  in  the  inner  ear,  where  they  produce  the 
sense  of  sound. 

8.  The  Eustachian  tube  leads  from  the  middle  ear  to  the 

back  part  of  the  nose.  A  cold  in  the  head  stops 
the  tube  and  causes  earache  and  deafness.  Most 
earaches  are  caused  by  a  cold  in  the  throat. 

9.  Little  particles  in  the  air  soak  through  the  wet  sides  of 

the  nose  and,  touching  the  nerves  beneath,  produce 
the  sense  of  smell. 

10.  A  substance  soaking  into  the  surface  of  the  tongue 

and  touching  its  nerves  excites  the  sense  of  taste. 

1 1.  Smell  and  taste  guard  us  against  bad  air  and  bad  food. 


Bones  of  the 


Head  and  Face. 


Clavicle,  or  Collar  Bone. 


Sternum,  or  Breastbone. 


Bones  of  Vertebral  Column. 


.—.Scapula,  or  Shoulder  Bone. 


Ribs 


Humerus. 


Pelvis,  including  (5.)  Sacrum  and 
(Cx.)  Coccyx. 


Patella. 


Tibia,  or  Large  Bone  of  Fore  Leg. 


Tarsus,  or  Ankle  and  Heel  Bones  (7). 
\Jones  of  foot.  —  Nineteen  bones. 


Ulna. 


Radius. 


Carpus,  or  Wrist.  —  Eight 

small  bones. 
i  Hand.  —  Nineteen  bones. 


Fibula,  or  small  Splint  Bone  of  Leg 


The  Human  Skeleton,  showing  position  of  bones. 
154 


CHAPTER   XVI 
BONES 

304.  Need   of  bones.  —  Besides   eating,   breathing,  and 
sleeping,  man's  body  does  a  great  deal  of  heavy  work  that 
would  crush  a  soft  body.     Man  also  goes  from  place  to 
place  and  carries  heavy  weights  that  he  could  not  carry 
if  he  did  not  possess  something  on  purpose  to  move  his 
body.     Inside  the  body  is  a  stiff  and  strong  frame  of  bone, 
which  is  moved  by  muscles.     Bones  form  the  frame  of 
nearly  every  part  of  the  body,  while  the  muscles  which 
cover  them  make  the  body  plump  and  round.     About  one 
seventh  of  the  body  is  bone,  while  over  one  half  is  muscle. 
In  all  there  are  over  two  hundred  bones  in  the  body. 

305.  Shape  of  bones.  —  Long  bones  extend  down  the 
arms  and  legs,  and  slender  bones  form  the  fingers  and  toes. 
Flat,   curved  plates  of  bone  form  the  skull.      Rounded 
bones  form  the  wrists  and  ankles,  and  rings  of  bone  form 
the  backbone.     Bones  are  of  different  shapes  in  order  to 
fit  into  the  different  parts  of  the  body. 

Each  long  bone  is  a  hollow  shell  like  the  frame  of  a 
bicycle.  This  makes  it  strong  and  yet  light.  Its  hollow 
inside  is  filled  with  a  soft  fat  called  marrow. 

The  ends  of  long  bones  are  like  a  fine  honeycomb 
covered  with  a  hard  shell  of  firm  bone.  This  makes  them 
light  and  yet  able  to  resist  the  pressure  of  the  body  above. 

306.  Strength  of  bone.  —  Each  bone  is  very  hard,  and 


APPLIED    PHYSIOLOGY 


yet   it  can   be  bent  somewhat  without  breaking.      It  is 
twice  as  strong  as  an  oak  stick  of  the  same  size. 

307.  Structure  of  bone.  —  A  bone  is  made  of  living  cells 
fed  by  the  blood.  From  the  cells  there  go  out  fine  strings 
of  connective  tissue.  Lime  is  mixed  among  the  strings 
like  starch  among  the  fibers  of  a  linen  collar.  This  makes 


a  bone  cells. 


Thin  slice  of  bone  ( X  200) . 

b  Haversian  canal,  containing  blood  vessels  and  nerves. 


the  bones  hard.  About  one  third  of  a  bone  is  made  of  the 
living  cells  and  two  thirds  is  lime.  Under  a  microscope 
we  can  see  that  the  cells  form  circles  around  small  blood 
tubes. 

A  bone  is  covered  with  a  tough  membrane  called  the 
periosteum.  The  periosteum  forms  new  cells  and  makes 
the  bone  grow.  If  the  bone  is  removed  and  its -periosteum 
left,  this  will  form  a  new  bone  in  a  few  weeks.  Bone 
grows  and  wastes  away,  but  it  changes  much  slower  than 
any  other  part  of  the  body. 

The  place  where  bones  join  together  is  a  joint.  Some 
joints  can  bend  and  others  cannot. 


BONES  157 

308.  The  skull.  —  The  frame  of  the  head  is  called  the 
skull.     It  is  made  of  twenty-two  flat  plates  of  bone.    Those 
that  cover  the  brain  and  the  other  parts  of  the  head  are 
thick  and  strong,  for  they  are  likely  to  be  hurt  by  blows. 
The  bones  which  make  the  nose  and  the  inside  of  the 
skull  are  thin,  for  they  have  little  work  to  do,  and  blows 
cannot  reach  them. 

The  bones  of  the  skull  are  joined  together  by  rough 
edges,  which  fit  exactly  into  each  other.  In  a  man  some 
of  these  bones  grow  together  into  a  single  bone.  These 
joints  can  move  only  enough  to  prevent  a  little  of  the 
jarring  when  we  jump  or  strike  the  head  against  something 
hard,  but  in  a  young  baby  the  bones  can  be  moved  and 
the  head  can  be  pressed  into  any  shape. 

309.  The  spine.  —  The  skull  is  balanced  upon  a  stiff 
string  of  bones  called  the  spine  or  backbone.     The  spine 
runs  the  whole  length  of  the  back,  and  is  made  up  of 
thirty-three  rings  of  bone;  but  in  a  man  the  lower  ones 
grow  together  so  that  there  are  only  twenty-six  separate 
rings.     The  spinal  cord  is  hung  in  the  middle  of  these 
rings.     Between  the  rings  are  thick,  strong  pads  of  tough 
flesh  or  gristle  which  make  strong,  close  joints,  and  also 
act  as  springs  to  keep  the  body  from  being  jarred  when 
we  run  or  jump.     By  means  of  these  joints  the  backbone 
can  be  bent  and  twisted,  but  the  motion  is  small.     In  the 
circus  are  men  whose  backbones  are  so  loose  jointed  that 
they  can  twist  themselves  into  a  knot. 

310.  Ribs.  —  From  the  sides  of  the  backbone  slender 
bones,  called  ribs,  extend  around  the  sides  of  the  body, 
and  are  joined  in  front  to  the  sides  of  a  flat  bone  called 
the    breast  bone.      There  are  twelve  ribs  on   each  side. 
They  have  a  little  motion  up  and  down,  and  out  and  in, 
as  in  breathing.     They  form  a  box  called  the  chest. 


158  APPLIED   PHYSIOLOGY 

311.  The   pelvis.  —  The   backbone  rests  upon   a  large 
and  strong  ring  of  bone  formed  by  the  hip  bones.     The 
hip  bones  form  a  round  bottomless  basin  called  the  pelvis, 
There  are  three  bones  in  the  pelvis,  and  the  joints  between 
them  are  close  fitting  and  strong.     We  sit  upon  the  bot- 
toms of  the  two  hip  bones. 

312.  The  legs.  —  From  each  side  of  the  pelvis  a  long 
bone  reaches  downward  to  form  the  framework  of  the  leg 
above  the  knee.     This  t bone  is  called  the  femur,  and  is 
the  largest,  longest,  and  strongest  bone  in  the  body. 

Reaching  from  the  knee  to  the  ankle  is  a  long  and 
strong  bone  called  the  shin  bone  or  tibia.  Upon  its  out- 
side is  a  long  slender  bone  called  the  fibula.  The  lower 
end  of  the  fibula  forms  ^the  lump  of  bone  which  is  called 
the  outer  ankle  bone.  The  inner  ankle  bone  is  formed  by 
a  small  tongue  of  bone  from  the  tibia. 

313.  The  instep.  —  Below  the  shin  bone  are  seven  small 
rounded  bones  which  are  very  tightly  bound  together  by 
strong  bands  of  connective  tissue.     They  form  the  instep, 
or  arch  of  the  foot.     This  arch  supports  the  weight  of  the 
body  while  we  stand.     So  it  is  made  very  strong.     A  single 
bone  would  not  spring,  but  the  whole  body  would  be  jarred 
at  every  step.     The  arch  is  made  of  several  bones  each  of 
which  will  spring  a  little.     So  when  ,we  jump  or  run,  our 
bodies  are  but  little  jarred.     The  pads  between  the  rings 
of  the  spine  also  keep  the  body  from  being  jarred. 

At  the  end  of  the  instep  are  nineteen  slender  bones 
joined  end  to  end  in  five  strings.  The  first  bone  of  each 
string  is  buried  in  the  flesh,  and  together  they  form  the 
sole  of  the  foot.  They  are  called  tarsal  bones.  The  re- 
maining bones  of  each  string  form  the  toes. 

314.  The  shoulder.  —  Two  bones  at  the  lower  part  of  the 
neck  upon  each  side  form  a  frame  upon  which  the  arm  is 


BONES  159 

hung.  The  bone  in  front  is  slender  and  long  and  is  called 
the  collar  bone,  or  clavicle.  Its  inner  end  rests  against  the 
breast  bone.  The  bone  behind  is  flat  and  forms  the  shoul- 
der blade,  or  scapula.  It  is  not  joined  to  any  bone,  but 
is  hung  only  by  muscles.  These  two  bones  form  the 
shoulder. 

315.  The  arm.  —  From  the  side  of  the  shoulder  a  long, 
strong  bone  hangs  down  to  form  the  frame  of  the  arm 
above  the  elbow.     It  is  called  the  humerus.     At  the  elbow 
it  joins  two  other  bones  which  form  the  frame  of  the  arm 
below  the  elbow.     The  bone  upon  the  thumb  side  of  the 
arm  is  called  the  radius,  and  upon  the  little  finger  side, 
the  ulna. 

316.  The  wrist  and  hand.  —  At  the  ends  of  the  radius 
and  ulna  are  eight  small,  rounded  bones  which  form  the 
wrist.     These  bones  are   firmly  joined  together  by  con- 
nective  tissue  like  the  tarsal  bones  of   the  foot.     They 
make  the  wrist  more  springy  than  it  would  be  if  it  were 
a  single  bone. 

At  the  lower  end  of  the  wrist  are  nineteen  slender  bones, 
joined  end  to  end  so  as  to  form  five  strings  of  bone  as  in 
the  foot.  The  first  bones  of  each  string  are  buried  in  the 
flesh  and  make  the  frame  work  of  the  palm  of  the  hand. 
The  outer  bones  of  each  string  form  the  fingers. 

317.  Hand  and  foot  compared.  —  The  hand  and  foot  are 
each  made  of  the  same  number  of  bones  and  upon  the 
same  plan.     The  instep  is  much  larger  and  stronger  than 
the  wrist,  for  it  must  bear  great  weights.     The  toes  are 
much  shorter  than  the  fingers,  but  they  have  the  same 
muscles  and  can  be  moved  in  the  same  ways.     The  great 
toe  cannot  be  turned  in  so  as  to  be  brought  against  the 
other  toes  as  the  thumb  can  against   the  fingers.      The 
foot  would  be  a  very  clumsy  hand,  yet  some  persons  who 


i6o 


APPLIED   PHYSIOLOGY 


have  been  born  without  hands  have  learned  to  use  their 
feet  instead. 

318.  Joints.  —  The  bones  of  the  skull  and  pelvis  can  be 
moved  but  little.     Their  joints  permit  these  bones  to  grow 
and  also  make  them  slightly  springy. 

The  bones  of  the  spine,  instep,  ribs,  and  wrist  can  move 
a  little.  Each  bone  moves  scarcely  enough  to  be  notice- 
able, but  altogether  they  have  a  considerable  range  of 
motion. 

The  bones  of  the  arms,  fingers,  legs,  and  toes  and  the 
lower  jaw  can  be  moved  freely.  In  them  the  end  of  one 
bone  is  rounded  and  fits  snugly  into  a  hollow  in  the  other 
bone.  .The  two  bones  are  bound  together  by  tough  bands 
called  ligaments,  which  encircle  the  joint  like  a  loose  col- 
lar. Thus  the  bones  are  free  to  move  like  a  door  upon 
its  hinges. 

319.  Cartilage. — The  ends  of  bones  in  the  joints  are 

covered  with  a  thin  layer  of  a  very 
tough  and  firm  substance  called  carti- 
lage. Cartilage  is  like  bone  without 
lime.  The  bone  of  young  animals  is 
cartilage  at  first,  but  as  it  grows  it 
takes  up  lime,  except  at  the  ends,  which 
remain  cartilage. 

320.  Synovial  membrane.  —  The  in- 
side of  a  movable  joint  is  lined  with  a 
bag  called  the  synovial  membrane. 
The  synovial  membrane  is  very  smooth 
and  is  filled  with  a  liquid  like  the  white 
of  an  egg.  This  oils  the  joint  and 
makes  it  work  smoothly.  Sometimes 

in  old  people  the  synovial  fluid  dries  up.     Then  the  joint 

is  stiff  and  creaks  when  it  is  bent. 


i- 


Hinge  joint  of  the  elbow, 
i  humerus  2  ulna 


BONES  l6l 

321.  Hinge  joints.  —  In  the  fingers,  toes,  wrists,  ankles, 
elbows,  and  knees  the  surfaces  of  the  joints  are  long  and 
round  like  a  hinge.     So  they  can  open  and  shut  in  one 
direction  only  like  a  penknife.     In  the  other  direction  they 
can  only  straighten  the  limb.     If  you  bend  the  limb  in  the 
wrong  direction,  you  will  break  the  bones  or  else  put  them 
out  of  joint. 

322.  Ball  and   socket  joints.  —  The  shoulders  and  hip 
joints  can  be  moved  in  any  direction.     In  each  the  upper 
end  of  the  bone  of  the  limb  is  round  like  half  of  a  ball. 
This  fits  into  a  cup  in  the  other  bone.     Thus  the  limb  can 
be  turned  in  any  direction.      In  fourfooted  animals  the 
fore  and  hind  legs  cannot  be  moved  nearly  so  freely  as  a 
man's  arms  and  legs.     So  these  animals  could  not  do  a 
man's  work  even  if  they  had  hands. 

323.  Broken  bones.  —  The  bones  of  children  are  more 
springy  and  are  softer  than  those  of  old  people.     A  child 
may  fall  very  hard  without  danger,  while  an  old  person's 
bones  will  break  from  a  slight  fall.     But  a  grown  person 
weighs  many  times  as  much  as  a  child,  and  so,  when*  he 
falls,  there  is  more  strain  on  the  bones. 

When  a  bone  is  broken,  its  ends  must  be  put  in  place, 
or  "  set,"  and  kept  there  by  splints  and  bandages.  Then 
new  cells  grow  in  place  of  the  injured  ones.  Lime  is 
mixed  with  the  new  cells,  and  the  bone  repairs  itself  in 
about  a  month.  It  will  then  be  as  strong  as  it  was  before 
it  was  broken,  or  even  stronger.  If  the  ends  of  the  bones 
are  not  put  in  their  proper  place  and  kept  there  until  heal- 
ing begins,  the  bone  will  grow  crooked. 

324.  Sprains. — When  a  joint  is  bent  too  far,  or  in  the 
wrong  direction,   its  ligaments  are  stretched  and   partly 
torn.     This   makes   a  sprain.      A   sprained  joint  is  very 
tender  and  painful,  and  gets  well  slowly. 

ov.  PHYSIOL.  (INTER.)  —  1 1 


162  APPLIED    PHYSIOLOGY 

When  you  sprain  a  joint,  you  should  put  it  at  once  in 
hot  water  for  an  hour  or  two.  This  will  relieve  the  pain 
and  swelling.  Then  you  should  keep  the  joint  at  rest  for 
a  few  days. 

325.  Bones  out  of  joint.  —  When  the  end  of  a  bone  is 
out  of  its  socket,  the  bone  is  out  of  joint.     Then  move- 
ments of  the  limb  will  be  painful  or  impossible.     If  a  bone 
gets  out  of  joint,  the  ligaments  become  badly  torn  and 
will  heal  slowly.     A  bone  out  of  joint  is  as  bad  an  injury 
as  a  broken  bone.     It  will  be  necessary  to  put  the  bone  in 
place  and  keep  it  there  by  splints  and  bandages.     It  is 
treated  like  a  broken  bone. 

326.  Effects  of  improper  positions.  —  When  a  bone  or 
joint  is  bent,  it  will  return  to  its  former  shape.     If  it  is 
kept  bent  in  one  direction  a  large  part  of  the  time,  it 
slowly  grows  into  that  shape.     If  you  always  lean  to  one 
side  while  sitting  at  the  desk,  the  backbone  will  finally 
become  curved  in  that  direction.     If  you  sit  round-shoul- 
dered, after  a  while  your  bones  and  joints  will  make  you 
keep  that  shape.     A  round-shouldered  person  has  small 
lungs.     He  is  apt  to  be  short-winded. 

327.  Tight  shoes.  —  If  your  shoes  are  tight,  they  will 
cramp  your  toes  and  make  them  grow  out  of  shape.     The 
big  toe  of  a  baby  points  forward  in  a  line  with  the  inside 
of  the  foot.     It  points  forward  in  very  few  men  or  women, 
for  their  tight  shoes  force  it  inward  until  it  stays  in  that 
position.     The  ends  of  the  toes  should  be  square  with  the 
sides  of  the  feet.     Tight  shoes  cramp  the  toes  and  make 
them  pointed.     When  the  tight  shoe  rubs  the  skin,  it  causes 
the  epithelium  to  thicken  and  form  a  corn.     If  it  forces  the 
big  toe  inward,  it  harms  its  joint,  making  it  swell  and  be- 
come painful.     This  forms  a  bunion.     The  cure  for  corns 
and  bunions  is  to  wear  loose  shoes  of  the  shape  of  the  foot. 


BONES  163 

By  sitting,  standing^  and  walking  erect,  we  can  make 
our  backbones  straight  and  our  chests  full.  A  soldier  is 
straight  because  he  has  had  to  keep  his  back  straight  until 
it  grew  so. 

SUMMARY 

I..  Two  hundred  bones  form  a  strong  frame  for  the  body. 
Some  are  long  and  some  are  flat. 

2.  Bones  are  made  of  living  cells,  in  which  lime  is  mixed 

to  give  them  stiffness. 

3.  The  union  of  two  bones  is  a  joint.     Some,  as  those  of 

the  head,  cannot  be  moved.  They  allow  the  bones 
to  spring  a  little  instead  of  breaking,  when  they  are 
hit  or  pressed. 

4.  The  bones  of  the  spine  can  move  a  little,  for  they  are 

joined  together  by  pads  like  rubber  cushions. 

5.  In  the  arms  and  legs  the  bones  fit  together  by  means 

of  rounded  surfaces.  They  are  covered  with  car- 
tilage and  are  held  in  place  by  loose  ligaments. 

6.  Joints  are  oiled  by  a  fluid  like  the  white  of  an  egg, 

called  the  synovial  fluid. 

7.  Most  joints  move  back  and  forth  like  a  hinge.     The 

shoulder  and  hip  can  be  moved  in  any  direction. 

8.  The  cells  of  a  broken  bone  soon  fill  in  the  gap  with 

the  new  cells,  and  then  deposit  lime  in  the  new 
part.  This  heals  the  bone. 

9.  In  sprains,  and  when  bones  are  out  of  joint,  the  liga- 

ments are  torn  and  require  a  long  time  to  heal. 
10.   When  the  body  keeps  an  improper  position  for  days 
at  a  time,  it  will  grow  into  that  position. 


The  muscular  system. 
164 


CHAPTER   XVII 

MUSCLES 

328.  Use  of  muscles.  —  The  bony  framework  of  the  body 
is  covered  and  rounded  out  by  muscles.  Muscles  form 
one  half  of  our  weight.  They  are  the  servants  of  the 
mind,  and  do  its  physical  work,  while  the  brain  does  its 

mental  work.  If  the  brain  and 
muscles  did  not  wear  out,  there 
would  be  no  need  of  a  stomach. 

As  it  is,  the  stomach,  heart, 
lungs,  and  other  parts  are  needed 
to  feed  and  to  keep  the  muscles 
and  brain  alive  and  well. 

Muslie  cells,  cut  across          329.    Structure    of    muscles.  — 
(X2oo).  Lean  meat  is  mostly  muscle.     A 

a  muscle  cell.  muscle  is  large  at  one  end  or  in 

b   connective  tissue  binding  the  & 

cells  together.  the  middle,  and  is  fast  to  a  bone. 

Its    other    end    generally    grows 

smaller  and  is  prolonged  in  a  strong  cord  called  a  tendon. 
The  tendon  crosses  a  joint  and  is  fast  to  another  bone. 

Each  muscular  bundle  is  made  of  cells  like  strings. 
These  are  the  largest  cells  in  the  body,  but  they  cannot 
be  seen  without  a  microscope.  They  are  bound  in  small 
bundles  by  delicate  strings  of  connective  tissue.  These 
bundles  are  bound  into  a  large  bundle  which  we  call  a 
muscle.  Each  large  bundle  of  muscle  is  covered  with  a 
thick  woven  skin  of  connective  tissue.  Finally,  all  the 

165 


166 


APPLIED   PHYSIOLOGY 


bundles  of  a  limb  are  bound  together  by  a  very  thick  sheet 

of  the  same  tissue.     You  can  see  these  bundles  and  their 

tough  coverings  in  any  meat. 

330.    Action  of  muscles.  —  A  nerve  thread  touches  every 

muscle  cell.     When  it  brings  an  order  to  act,  each  muscle 

cell  makes  itself  thicker  and 
shorter.  Thus  the  whole  muscle 
becomes  shorter  and  pulls  upon 
whatever  is  fast  to  its  ends. 
The  usual  action  of  a  muscle 
is  to  bend  a  joint. 

The  messages  sent  to  the  mus- 
cles come  from  the  cells  of  the 
spinal  cord.  They  send  mes- 
sages to  the  muscles  either  in 


c  connective    tissue  binding  the 
cells  together. 


A  thin  slice  of  a  voluntary  mus- 
cle, cut  lengthwise  ( x  100) . 
a  muscle  cell.  n 

b  capiiia-ries  surrounding  the  cells,    a  reflex  way  or  when  told  to  do 

so  by  the  cells  of  the  brain. 
Muscle  and  brain  cells  are  the 
only  cells  of  the  body  which  can  be  made  to  act  when- 
ever we  wish  them  to. 

331.  Involuntary  muscles. — There  is  a  kind  of  muscle 
which  we  cannot  make  act  by  an  effort  of  the  will,  but 
which  the  spinal  cord  keeps  in  action  in  a  reflex  way 
without  our  knowledge.  Such  muscles  are  found  in  the 
stomach,  intestine,  arteries,  and  skin.  They  are  the 
muscles  which  aid  the  digestion  of  food  and  the  flow  of 
blood.  The  spinal  cord  and  sympathetic  system  send  them 
orders  without  our  knowledge.  It  is  well  that  nature  has 
put  these  muscles  beyond  our  control,  for  we  might 
forget  to  attend  to  them.  They  are  called  involuntary 
muscles,  because  we  cannot  make  them  act.  These  mus- 
cles are  made  of  cells  with  long  pointed  ends.  Instead  of 
being  solid  masses,  they  form  thin  leaves  around  tubes. 


MUSCLES  167 

332.  How  to  see  muscles.  —  Shut  the  hand  tightly,  and 
notice  that  the  arm  just  below  the  elbow  becomes  harder 
and  larger.     This  is  because  the  muscles  which  shut  the 
hand  are  situated  upon  the  arm.     You  can  feel  and  see 
the  ridges  formed  by  each  bundle  of  muscle  while  it  is 
acting.    You  can  feel  their  tendons  as  they  cross  the  wrist. 
Some  end  in  the  palm  of  the  hand,  and  some  go  on  to  the 
fingers.     There  are  a  few  small  muscles  in  the  palm  of 
the  hand,  but  most  of  the  finger  muscles  are  in  the  arm. 
There  are  no  muscles  at  all  in  the  fingers. 

The  muscles  of  the  foot  are  upon  the  leg  below  the 
knee.  They  end  in  tendons  which  go  to  the  toes  like  the 
tendons  to  the  fingers.  The  tendon  above  the  heel  sup- 
ports the  weight  of  the  body  when  we  stand  on  tiptoe.  It  is 
the  largest  in  the  body,  and  is  called  the  tendon  of  Achilles. 

Muscles  which  bend  a  joint  are  usually  much  stronger 
than  those  which  straighten  it,  for  most  of  our  work  is 
done  by  bending  the  joints. 

333.  Strength  of  muscle.  —  Lean  meat  seems  soft  and 
almost  like  jelly,  yet  it  can  contract  with  great  force.    The 
muscle  upon  the  front  of  a  man's  arm  can  put  forth  a  force 
of  nearly  a  thousand  pounds,  but  its  tendon  is  attached  so 
near  the  elbow  that  we  can  really  lift  about  a  hundred 
pounds  with  the  hand.     Most  muscles  have  to  put  forth  a 
strength  more  than  equal  to  the  weight  which  they  move. 

A  grasshopper  seems  to  be  very  strong,  for  it  can  jump 
a  hundred  times  its  own  length.  But  a  grasshopper  is 
very  light,  and  has  but  little  weight  to  carry.  A  piece  of 
man's  muscle  of  the  size  of  a  grasshopper's  is  really  far 
the  stronger. 

334.  How  to  increase  the  strength.  —  By  use,  a  muscle 
becomes  larger  and  stronger.     When  a  boy  wishes  to  go 
into  a  race,  he  uses  the  muscles  of  his  legs  every  day  until 


1 68  APPLIED    PHYSIOLOGY 

they  are  large  and  hard,  and  he  can  run  very  fast  and 
long  without  getting  tired.  But  using  the  muscles  of  the 
leg  does  not  make  the  arm  stronger.  We  must  use  every 
muscle  if  we  would  get  strong  all  over. 

If  we  stop  using  our  muscles,  they  soon  become  weak 
again.  If  you  break  your  leg  and  have  to  keep  it  still,  it 
will  soon  become  small  and  weak.  Then  the  other  one  will 
grow  larger,  for  it  has  to  work  harder  to  carry  you  around. 

If  you  use  your  muscles  until  you  strain  them,  they  will 
grow  weaker  instead  of  stronger,  for  you  will  wear  them 
out  faster  than  the  blood  can  feed  them.  You  ought  not 
to  strain  yourself  trying  to  lift  as  much  as  a  grown  man 
lifts,  or  to  run  as  far  as  a  large  boy  runs. 

335.  Round  shoulders.  —  The  muscles  of  our  backs  hold 
us  erect  and  keep  our  shoulders  thrown  back.     A  lazy  boy 
lets  his  shoulders  fall,  and  supports  himself  by  leaning 
against  the  wall.     Sometimes  braces  are  used  to  keep  the 
shoulders  back.     This  rests  the  muscles,  and  lets  them 
grow   still   weaker.      The   best   way   to    make   the   body 
straight  is  to  make  the  muscles  hold  the  shoulders  back. 
This  is  what  soldiers  do.     Military  drill  tends  to  make 
boys  straight.     Working  women  of   Europe  often  carry 
heavy  burdens  upon  their  heads.     In  order  to  do  this,  they 
must  walk  erect  and  steady.     These  women  are  noted  for 
their  straight  backs  and  graceful  walk.     A  drill  in  carrying 
loads  upon  the  head  would  be  of  great  value  in  making 
young  girls  walk  gracefully. 

336.  How  exercise  makes  the  body  healthy.  —  The  mus- 
cles are  the  engine  of  the  body.     The  food  is  the  fuel. 
Oxygen  burns  the  food  and  makes  heat,  which  the  muscles 
turn  to  power.     When  a  muscle  acts,  it  needs  a  great  deal 
of  heat.     So  it  must  have  more  food  and  air,  which  is 
brought  by  the  blood.     In  order  to  support  it,  the  heart 


MUSCLES  169 

beats  faster  and  stronger  and  the  stomach  acts  better. 
The  whole  body  does  better  work  so  as  to  supply  the 
muscles  with  power.  The  brain  also  feels  the  effects  of 
the  increased  action  of  the  body.  Use  of  the  muscles 
makes  us  feel  better  in  every  way.  When  we  have  studied 
or  written  all  day,  we  have  taken  only  a  few  deep  breaths. 
Our  fires  burn  low  and  become  clogged  with  waste  matter. 
If  we  now  exercise  for  a  few  minutes,  we  shall  start  up  all 
the  actions  of  the  body  and  shall  feel  fresh  again. 

Some  men  work  hard  and  are  healthy  until  they  get 
rich.  Then  they  stop  work  at  once  and  try  to  enjoy  their 
rest.  But  they  find  that  their  food  does  not  digest,  and 
that  they  cannot  breathe  well.  Their  brains  are  clouded 
and  their  heads  ache.  The  trouble  is  that  their  muscles 
do  not  need  food,  and  so  the  body  does  not  prepare  it  for 
them.  If  they  should  do  light  work,  they  would  feel  all 
right. 

We  can  use  our  muscles  in  order  to  grow  strong.  This 
alone  will  not  do  us  much  good,  for  men  can  use  machines 
to  do  far  more  hard  work  than  a  large  number  of  men  can 
do.  We  also  use  our  muscles  so  as  to  grow  healthy.  This 
should  be  the  object  of  exercise.  Every  one  should  do 
some  work  with  his  muscles  every  day.  Girls  and  women 
need  exercise  as  well  as  boys  and  men. 

337.  How  to  exercise.  —  The  best  exercise  is  that  in 
which  some  useful  work  is  done.  A  farmer's  boy  grows 
strong  and  does  not  think  of  his  exercise.  Work  about 
the  house  or  barn  is  the  best  kind  of  exercise.  Every 
child  should  have  some  regular  work  to  do  night  and 
morning.  It  will  make  him  stronger  and  will  also  teach 
him  how  to  work. 

It  is  well  to  teach  boys  and  girls  some  trade.  Carpen- 
tering is  exercise,  and  also  gives  them  useful  knowledge. 


APPLIED   PHYSIOLOGY 

Gardening  and  housework  are  also  exercise,  and  should  be 
taught  to  every  child. 

A  bicycle  affords  good  exercise.  If  a  person  does  not 
race  or  go  on  long  rides,  it  will  do  him  no  harm.  Even 
old  men  and  very  small  children  can  ride  it  safely. 

Gymnasiums  are  of  great  value  in  taking  exercise.  By 
the  use  of  dumb-bells  and  Indian  clubs,  and  by  lifting 
light  chest  weights,  any  weak  part  of  the  body  can  be 
made  strong.  The  only  trouble  in  the  use  of  these  is  that 
we  soon  get  tired  of  one  thing.  In  classes  and  under  a 
teacher  they  afford  interesting  and  profitable  exercise. 

338.  The  face  muscles. — The  muscles  of  the  face  are 
flat  and  fastened  to  the  skin.  When  they  act,  they  draw 


Illustration  of  the  change  of  expression  produced  by  the  muscles 
of  the  mouth. 

and  pucker  the  skin  in  different  directions.  Each  kind  of 
feeling  in  the  mind  causes  the  muscles  to  act  in  a  certain 
way.  If  we  feel  happy,  the  muscles  draw  the  ends  of  the 
mouth  upward  and  backward.  This  makes  a  smile.  If 
we  feel  sad,  the  muscles  draw  the  ends  of  the  mouth 
down.  By  looking  at  a  person's  face  we  can  often  tell 
how  he  is  feeling. 

339.  Effects  of  alcohol  and  tobacco.  —  Alcohol  appro- 
priates oxygen  belonging  to  the  muscle  cells  and  prevents 
the  stomach  and  liver  from  preparing  food  for  their  use. 


MUSCLES  I /I 

Consequently,  it  weakens  the  muscles.  It  may  seem  to 
make  a  person  stronger,  for  it  deadens  his  tired  feelings. 
But  in  reality  he  has  less  strength  than  if  he  had  let  drink 
alone.  A  single  drink  begins  to  weaken  him.  Alcohol 
cannot  take  the  place  of  food,  for  food  is  the  only  thing 
to  give  strength  to  the  body.  Drugs  may  deaden  tired 
feelings,  but  they  cannot  add  to  one's  strength. 

Alcohol  sometimes  causes  little  drops  of  the  muscle 
cells  to  change  to  fat.  This  greatly  weakens  the  cells. 
Beer  often  does  this.  A  man  may  seem  to  be  very  fat 
and  strong  from  its  use,  but  fat  does  not  give  strength. 

Tobacco  is  a  poison  to  all  the  cells  of  the  body,  and  it 
never  becomes  anything  else.  No  man  who  is  training 
for  a  race  dares  to  use  tobacco. 

340.  Alcohol  and  endurance.  —  Men  sometimes  have  to 
make  long  journeys  across  hot  deserts  or  in  cold  Arctic 
regions,  or  have  to  endure  great  fatigue  and  suffering  in 
war.  It  used  to  be  thought  that  strong  drink  gave  men 
greater  power  for  undergoing  these  heavy  labors,  and  so 
men  in  armies  and  exploring  expeditions  always  carried 
regular  supplies  of  rum,  which  was  doubled  just  before  a 
battle  or  an  extra  strain.  Men  who  refused  to  drink  were 
laughed  at ;  but  it  was  noticed  that  they  did  more  work 
and  enjoyed  better  health  than  the  drinkers.  Then  care- 
ful experiments  were  made  to  determine  whether  men 
could  do  without  liquor.  In  every  case  men  in  hot  cli- 
mates felt  better,  while  those  in  polar  regions  endured  the 
cold  better  than  those  who  used  it.  The  government 
of  the  United  States  long  since  stopped  giving  liquor  to 
the  soldiers  and  sailors.  Arctic  explorers  do  not  carry  it 
except  for  scientific  purposes.  Even  hard  drinkers  care- 
fully avoid  liquor  while  they  are  training. 

A  few  years  ago  a  man  would  have  been  called  foolish 


1/2  APPLIED   PHYSIOLOGY 

if  he  did  not  drink  while  doing  hard  work.  Mowers  each 
took  a  drink  from  a  common  jug  at  each  round  of  the  field. 
One  man  remarked,  "  I  could  mow  without  rum  as  well  as 
any  one  if  it  were  not  for  the  looks  of  the  thing."  Rum 
was  used  freely  at  every  church  raising.  Now  all  this  has 
changed.  Fashion  no  longer  requires  men  to  drink.  On 
the  other  hand  there  is  a  growing  knowledge  of  its  harm, 
and  an  increasing  custom  of  letting  drink  alone. 

341.  Tobacco   and   strength.  —  Formerly   men   thought 
that  tobacco  helped  men  to  work  hard  and  to  endure  fa- 
tigue.    Now  men  know  better,  but  because  its  effects  are 
not  so  great  as  those  of  alcohol,  men  are  slower  in  giving 
up  its  use.     Still  its  effects  are  so  great  that  men  who 
train  for  races  will  not  use  it  any  more  than  they  would 
strong  drink. 

It  is  everywhere  admitted  that  the  use  of  tobacco  by  the 
young  hinders  the  growth  of  the  body.  Careful  measure- 
ments of  young  men  in  schools  and  colleges  show  that 
smokers  do  not  grow  so  fast  nor  so  large  as  those  who 
do  not  smoke.  Cigarettes  are  especially  harmful  to  the 
young,  and  yet  boys  and  young  men  are  almost  the  only 
persons  who  buy  them. 

342.  Life  insurance  and  drinking.  —  The  most  convinc- 
ing proof  of  the  evil  effects  of  strong  drink  is  the  records 
of  life  insurance  companies.     When  a  person  asks  to  be 
insured  the  company  makes  a  careful  inquiry  and  an  ex- 
amination to  find  out  the  state  of  the  candidate's  health  and 
his  habits  in  regard  to  drinking.      If  he  is  accepted  he  pays 
a  certain  sum  each  year.     Then,  after  a  certain  number  of 
years,  or  at  his  death,  a  sum  of  money  is  paid  to  him  or  to 
his  family.     A  person  at  any  given  age  may  be  expected 
to  live  and  to  pay  premiums  for  a  certain  number  of  years. 
Some  die  sooner  and  some  live  longer;  but  the  amount 


MUSCLES  1/3 

which  they  all  pay  nearly  equals  the  amount  which  the 
company  had  calculated  they  would  have  paid  if  all  had 
lived  a  given  number  of  years.  According  to  life  insur- 
ance tables  a  healthy  man,  at  20  years  of  age  may  expect 
to  live  44  years  more ;  at  30  years  of  age,  36  years  more ; 
and  at  40  years  of  age,  28  years  more.  If  a  man  is  a  mod- 
erate drinker,  at  20  years  of  age,  he  may  expect  to  live  15 
years  more ;  at  30  years  of  age,  14  years  more ;  and  at  40 
years  of  age,  1 1  years  more.  As  a  mere  matter  of  busi- 
ness a  company  will  not  insure  a  drinker,  for  they  cannot 
afford  to  pay  a  large  sum  of  money  if  the  person  is  not 
likely  to  live  long  to  make  them  yearly  payments.  Thus, 
a  healthy  man  insured  at  20  years  of  age,  will  make  yearly 
payments  for  20  years  longer  than  a  drinker. 

343.  Why  strong  drink  shortens  life.  —  Strong  drink  is 
a  poison  which  is  strong  enough  to  produce  death  in  itself. 
A  great  many  drinkers  die  from  the  effects  of  strong  drink 
alone. 

Strong  drink  also  weakens  the  body  so  that  it  cannot 
resist  diseases  which  it  otherwise  could  endure.  In  epi- 
demics of  small  pox,  cholera,  yellow  fever,  and  such  deadly 
diseases,  drinkers  are  more  apt  to  take  the  disease  than 
those  who  do  not.  Of  the  sick,  drinkers  are  the  first  and 
often  the  only  ones  to  die.  Surgeons  hesitate  to  oper- 
ate upon  drinkers,  for  their  wounds  heal  slowly,  and  they 
take  chloroform  poorly.  It  is  true  that  some  drinkers 
escape  the  greater  dangers  of  alcohol,  but  the  risk  that  a 
drinker  runs  of  being  seriously  harmed  or  killed,  is  far 
greater  than  the  risk  that  a  soldier  runs  of  being  hurt  in 
a  battle. 

344.  A  long  life.  —  A  healthy  body  is  the  noblest  work  of 
nature.    Such  signs  as  hunger  and  taste  lead  man  to  nourish 
his  body,  and  pain  and  fatigue  warn  him  to  avoid  dangers. 


APPLIED   PHYSIOLOGY 

If  he  heeds  these  signs  his  mind  and  body  will  work 
together  as  one  for  seventy  years  and  more.  He  will  be 
able  to  resist  germs  of  disease,  while  no  cause  of  sickness 
will  arise  within  the  body  itself.  He  will  go  through  life 
with  a  buoyant  sense  of  strength,  eager  to  do  the  work 
which  his  thoughts  are  ever  planning. 

SUMMARY 

1.  Muscles  cover  the  bones  and  move  the  joints. 

2.  A  muscle  is  a  bundle  of  stringlike  cells.     When  nerves 

bring  it  orders  to  act,  it  makes  itself  shorter  and 
pulls  its  ends  together. 

3.  A  muscle  usually  ends  in  a  long  tendon  which  crosses 

a  joint  and  is  fastened  to  another  bone. ' 

4.  Muscles  are  lean  meat.     They  can  be  felt  in  the  arms 

and  legs. 

5.  By  use,  a  muscle  grows  larger  and  stronger. 

6.  By  too  great  use,  a  muscle  is  used  up  faster  than  the 

blood  builds  it  again. 

7.  The  power  of  a  muscle  comes  from  the  heat  of  oxi- 

dized food. 

8.  In  exercise  a  muscle  needs  more  food  and  air,  which 

the  stomach,  heart,  and  lungs  supply  by  working 
harder. 

9.  Useful  and  interesting  work  is  the  best  exercise. 

10.  Alcohol  keeps  the  stomach  from  preparing  food  for 
-    the  muscles,  and  takes  away  their  oxygen.     Thus  it 

diminishes  their  strength. 

11.  Tobacco  poisons  the  muscles. 

12.  By  living  as  well  as  we  know  how,  we  shall  keep  the 

body  strong  and  healthy  until  old  age. 


GLOSSARY. 


•     A. 

Ab-do'men,  the  inside  of  the  lower  part  of  the  body. 

Abscess  (a&'sess),  a  collection  of  creamy  matter  in  the  flesh,  as  a  boil. 

A-chil'les,  an  old  Greek  warrior  who  could  not  be  harmed  excepting  in 

the  heel,  where  he  finally  received  his  death  wound.      Hence  the 

tendon  at  the  heel  is  named  after  him. 
A-dul'ter-ate,  to  mix  a  poor   substance   with  a  better  one  so  as  to 

sell  the  whole  for  the  price  of  a  good  article. 
Al-bu'min,  a  substance  in  the  body  like  the  white  of  an  egg.     It  is 

found  in  all  living  cells  and  must  be  supplied  with  the  food. 
Al'co-hol,  a  clear  liquid  of  a  burning  taste  and  smell.     It  is  found  in 

all  strong  drinks  and  gives  them  their  poisonous  qualities. 
A-me'ba,  a  low  form  of  animal  consisting  of  a  single  microscopic  lump 

of  albuminous  jelly. 

Ap'pe-tite,  the  desire  for  food  or  drink ;  the  desire  to  satisfy  a  taste. 
Ar'ter-y,  a  tube  which  carries  blood  away  from  the  heart  and  toward 

the  cells  of  the  body. 
Ar-ti-fi'cial  res-pir-a'tion,  causing  air  to  pass  in  and  out  of  the  lungs 

of  an  insensible  person. 
Au'ri-cle,  one  of  the  two  thin  upper  pockets  of  the  heart. 

B. 

Bac-te'ri-a,  the  simplest  form  of  living  beings.  They  are  plants  like 
tiny  balls  or  rods.  They  produce  decay,  and  some  produce  disease 
in  the  human  body.  They  are  also  called  microbes  and  germs. 

Bile,  a  bitter  yellow  fluid  formed  by  the  liver  and  poured  into  the 
intestine.  It  is  a  waste  product,  but  on  its  way  out  of  the  body  it 
assists  digestion. 

Brain  (brane),  the  nervous  matter  in  the  skull.  By  means  of  it  we 
think,  feel,  and  move. 

Bron'chus,  one  of  the  wind  tubes  of  the  lung. 


1 76  GLOSSARY 

C. 

Cal'lus,  a  hard  and  thick  spot  of  epithelium  upon  the  skin.     It  comes 

as  a  result  of  work,  to  protect  the  skin  from  injury. 
Cap'il-la'ry,  one  of  the  fine  tubes  into  which  arteries  pour  the  blood. 

They  surround  each  cell  and  give  out  blood  and  air  to  it. 
Car-bon'ic  a'cid,  a  gas  formed  by  burning  and   by  oxidation  in  the 

body.     It  is  given  off  in  the  breath. 
Car'ti-lage,  a  substance  which  covers  the  ends  of  bones  within  joints. 

It  is  often  called  gristle.     It  is  like  bone  without  lime. 
Cell,  the  smallest  part  of  the  body  which  can  live  when  separated  from 

the  rest.     The  smallest  unit  of  the  body.     A  cell,  when  cut,  dies. 
Cer-e-bel'lum,  the  rounded  part  of  the  brain  projecting  backward  from 

its  under  side.     It  assists  in  performing  movements  of  balancing. 
Cer'e-brum,  the  large  upper  part  of  the  brain.     It  feels,  thinks,  and 

produces  motion  in  the  rest  of  the  body. 
Chloral  (klo'ral},  a  peppery-tasting,  poisonous  solid  which  produces 

sleep. 
Cilia  (siVi-a\  tiny  waving  hairs  upon  the  surface  of  cells.     They  are 

found  in  the  epithelial  ceils  lining  the  air  tubes. 
Cir-cu-la'tion,  the  flow  of  blood  through  the  body. 
Glav'i-cle,  the  collar  bone.  It  extends  from  the  middle  of  the  front  of 

the  body  to  the  shoulder. 

Co'ca-ine,  a  substance  which  benumbs  feeling  when  applied  to  nerves. 
Cold,  a  sickness  caused  by  exposure  to  cold  and  dampness.     This 

injures  the  cells  and  permits  bacteria  of  disease  to  grow  upon  them 

and  produce  disease. 
Con-nect'ive  tis'sue,  the  fine  fibers  which  bind  the  cells  of  the  body  in 

place. 

Cook'ing,  the  preparation  of  food  for  eating  by  the  use  of  heat. 
Cor'ne-a,  the  round,  clear  window  in  the  front  of  the  eye,  which  admits 

light  to  the  inside. 
Cor'pus-cle,  a  cell  found  in  the  blood. 

D. 

De-lir'i-um  tre'mens,  a  mental  trouble  in  which  the  mind  seems  to 
see  foul  animals  and  reptiles.  It  is  caused  by  strong  drink. 

Der'ma,  the  true  skin.  It  forms  almost  the  entire  thickness  of  the 
skin,  and  contains  its  nerves  and  blood  tubes. 


GLOSSARY  177 

Di-ges'tion,  the  process  of  changing  food  to  a  liquid  which  will  pass 

through  the  sides  of  a  capillary  and  into  the  blood. 
Dis-til-la'tion,  changing  a  liquid  to  steam,  and  then  collecting  and 

cooling  the  steam  until  it  forms  a  liquid  again.    It  is  used  in  making 

alcohol  and  in  obtaining  pure  water. 
Drug,  a  substance  which  can  affect  the  body  when  taken  in  a  small 

quantity.     A  medicine. 

E. 

En-am'el,  the  hard  outer  shell  of  a  tooth. 

Energy  (en'er-jy},  force  which  can  be  used  to  make  a  machine  work. 

The  energy  of  the  body  comes  from  burning  or  oxidizing  the  food. 
Ep-i-der'mis,   the  thin  outside  part  of  the  skin,  which  has  no  feeling. 

It  is  composed  of  cells  of  epithelium. 
Ep-i-the'li-um,  the  cells  which  cover  the  surface  of  the  skin  and  of 

mucous  membranes,  and  which  line  the  tubes  of  all  glands. 
E-soph'a-gus,  the  tube  down  which  food  is  swallowed. 
Eustachian  (Yu-sta1  ki-an}  tube,  the  tube  leading  from  the  middle  ear 

to  the  throat.     It  is  named  after  an  Italian  physician  who  died 

in  1574. 
Ex-pi-ra'tion,  driving  air  from  the  lungs. 

F. 

Faint'ing,  losing  the  senses,  with  great  paleness.  It  is  caused  by  a 
sudden  weakness  of  the  heart,  often  due  to  fright. 

Fe'mur,  the  thigh  bone,  reaching  from  the  hip  to  the  knee. 

Fe'ver,  a  sickness  in  which  the  heat  of  the  body  is  increased. 

Fib'u-la,  the  bone  extending  from  the  knee  to  the  ankle  upon  the  out- 
side of  the  leg. 

Fil'ter,  a  box  filled  with  sand,  charcoal,  or  other  porous  substance. 
It  takes  impurities  out  of  water  which  is  run  through  it. 

Food,  anything  which,  when  taken  into  the  body,  can  add  to  its  weight, 
or  become  oxidized  and  produce  heat  and  energy. 

G. 

Gan'gli-on,  a  collection  of  nerve  cells,  especially  those  in  the  sympa- 
thetic system. 

Gas'tric  juice,  the  fluid  which  the  stomach  forms  to  digest  food, 
ov.  PHYSIOL.  (INTER  J  —  12 


1/8  GLOSSARY 

Germs,  tiny  living  plants  which  cause  catching  diseases.     They  are 

also  called  bacteria  and  microbes. 
Gland,  a  collection  of  tubes  made  of  epithelial  cells  which  produce 

a  substance  out  of  the  blood. 

H. 

Heart,  the  muscular  pump  which  forces  blood  through  the  body. 
He-red'i-ty,  the  influence  which  is  transmitted  at  birth  from  parents  to 

children. 
Hu'mer-us,  the  bone  of  the  upper  arm,  extending  from  the  shoulder  to 

the  elbow. 

I. 

In-flam-ma'tion,  heat,  swelling,  redness,  and  pain  in  a  part.     It  is  the 

result  of  an  injury  and  generally  is  associated  with  the  growth  of 

disease  germs. 

The  heat,  swelling,  and  redness  are  due  to  an  increased  flow  of  blood 

to  repair  the  injury.     The  pain  is  due  to  pressure  upon  the  nerves 

owing  to  the  increased  flow  of  blood. 
In-spi-ra'tion,  taking  air  into  the  lungs. 
In'step,  the  arch  of  the  foot. 
In-tem'per-ance,  eating  or  drinking  for  mere  pleasure,  or  when  the 

body  does  not  require  nourishment. 
In-tes'tine,  the  tube  in  the  lower  part  of  the  body,  into  which  food 

passes  from  the  stomach,  and  in  which  it  is  mainly  digested. 
In-vol'un-ta-ry  mus'cle,  a  muscle  which  acts  without  regard  to  our 

knowledge  or  effort,  as  the  muscle  of  the  heart  or  stomach. 

J- 

Joint,  the  union  of  two  bones,  whether  flexible  or  not. 

K. 

Kid'ney,  a  red  gland  which  separates  urea  and  other  waste  matters 
from  the  blood. 

L. 

Lac'te-al,  one  of  the  lymphatic  tubes  which  begin  in  a  villus  and  earry 

away  digested  fat. 
Larynx  (Jar' inks),  the  box  made  of  cartilage  situated  at  the  beginning 

of  the  windpipe.     In  it  the  voice  is  produced. 


GLOSSARY  179 

Lens,  a  part  of  the  eye,  shaped  like  a  small  burning  glass.     It  brings 

light  to  a  point  and  forms  an  image  of  an  object  upon  the  back  of 

the  eyeball. 

Lig'a-ment,  the  tough  bands  which  bind  bones  together  at  joints. 
Liv'er,  the  gland  above  the  stomach  which  forms  the  bile  and  changes 

digested  food  to  blood. 
Lung,  a  spongy  bag  from  which  the  red  blood  cells  get  air  to  carry  to 

the  cells  of  the  body. 
Lymph,  the  part  of  the  blood  which  leaves  the  capillaries  to  feed  the 

cells. 

Lym-phat'ics,  the  fine  tubes  which  carry  lymph  back  to  the  blood. 
Lymph  nodes,  small  bodies  through  which  lymph  flows  as  through  a 

sponge.     These  can  be  felt  in  the  groin  and  neck.     They  strain 

poisons  from  the  lymph. 

M. 

Malt,  barley  sprouted  and  grown  until  the  new  shoots  are  about  half  an 

inch  in  length,  and  then  dried.     It  is  used  in  making  beer. 
Mar'row,  the  fat  from  the  inside  of  hollow  bones. 
Me-dul'la,  the  part  of  the  brain  just  above  the  spinal  cord.     It  sends 

orders  for  the  movements  of  respiration. 
Mem'o-ry,  an  action  of  the  brain  which  can  be  recalled. 
Mi'crobes,  disease  germs.     The  same  as  bacteria  and  germs. 
Mi'cro-scope,  an  arrangement  of  glasses  which  make  small  things  seem 

large  to  the  sight. 
Mo'tor  nerves,  nerves  which  carry  impressions  away  from  the  brain, 

and  toward  the  cells  of  the  body.     These  impressions  cause  the 

cells  either  to  grow,  or  to  move. 
Mu'cous  mem'brane,  the  skinlike  lining  of  the   inside  parts  of  the 

body  which  connect  with  the  air.     It  lines  the  passages  by  which 

food  and  air  are  taken  in. 
Mu'cus,  the.  thin  slimy  fluid  which  mucous  membranes  produce.     It  is 

to  the  mucous  membranes  as  the  sweat  is  to  the  true  skin. 
Mus'cle,  a  collection  of  cells  whose  duty  is  to  produce  motion. 

N. 

Nar-COt'ic,   any  drug  which  will  benumb  pain  and   produce  sleep,  as 

opium. 
Nerve,  a  collection  of  threads  which  carry  messages  between  the  cells 

of  the  spinal  cord  or  brain  and  the  cells  of  the  body. 


ISO  GLOSSARY 

Ner'vous-ness.  a  lack  of  control  of  the  mind  over  the  messages  of  the 

nerves.     When  slight  impressions  of  the  nerves  cause  discomfort,  a 

person  is  nervous. 
Nic'o-tine,  a  very  poisonous  liquid  found  in  tobacco.     It  gives  tobacco 

its  taste  and  smell,  and  produces  its  poisonous  effects. 
Ni'tro-gen,  a  gas  which   forms  f  of  the  air.      It  has  no  effect  on  the 

body,  but  its  only  use  is  to  dilute  the  oxygen. 

O. 

0-le-o-mar'ga-rine,  an  imitation  of  butter,  made  of  beef  fat. 

0  pi-um,  the  juice  of  the  poppy  plant.     It  benumbs  pain  and  produces 

sleep,  and  is  thus  a  narcotic.     Some  men  learn  to  use  it  as  others  do 

tobacco.     It  is  a  poison. 
Ox-i-da'tion,  the  union  of  oxygen  with  a  substance;    burning.      In 

breathing,  oxygen  from  the  air  unites  with  the  cells  of  the  body, 

slowly  burning  them,  and  producing  heat. 
Ox'y-gen,  a  gas  which  forms  one  fifth  of  the  air.     Its  uniting  with  other 

substances  is  burning. 

P. 

Pan'cre-as,  the  gland  which  forms  the  pancreatic  juice  ;  the  sweet-bread. 
Pan-cre-at'ic  juice,  the  fluid  which  the  pancreas  pours  into  the  intestine. 

It  does  most  of  the  work  of  digestion. 
Pa-ral'y-sis,  a  state  of  the  body  in  which  it  is  impossible  to  move  or  to 

use  some  of  its  parts. 
Pel'vis,  the  heavy  ring  of  bone  formed  mainly  by  the  hip  bones.     Its 

inside  contains  a  part  of  the  intestine. 
Per-i-os'te-um,  the  tough,  skinlike  membrane  covering  the  bones,  and 

carrying  their  blood   tubes.     It   produces  new  bone  cells   and  so 

causes  a  bone  to  grow. 

Per-spi-ra'tion,  the  fluid  produced  by  the  skin ;  the  sweat. 
Pharynx  (far* inks),  the  muscular  bag  back  of  the  nose  and  mouth. 

Through  it  both  food  and  air  pass. 
Plas'ma,  the  liquid  part  of  the  blood. 
Poi'son,  a  substance  which  can  harm  the  body  when  taken  in  a  small 

quantity. 
Pu'pil,  the  round  opening  in  the  iris  or  colored  part  of  the  eye.     It 

appears  black. 
Pus,  the  white,  creamy  matter  in  a  boil  or  other  abscess. 


GLOSSARY  I8l 

R. 

Ra'di-us,  the  bone  upon  the  thumb  side  of  the  arm,  extending  from  the 

elbow  to  the  wrist. 
Re'flex  ac'tion,  the  act  of  the  spinal  cord  in  sending  orders  for  action 

in  response  to  information  from  the  cells.     It  provides  for  the  wants 

and  for  the  protection  of  the  cells. 

S. 

Sa-li'va,  the  fluid  always  found  in  the  mouth.     It  moistens  the  mouth, 

softens  food,  and  turns  starch  to  sugar. 

Scap'u-la,  the  flat  bone  behind  the  shoulder;  the  shoulder  blade. 
Sen'ses,  the  five  means  by  which  the  mind  gets  knowledge  of  the  world 

outside  of  the  body.     They  are  seeing,  hearing,  feeling,  smelling, 

and  tasting. 
Sen'so-ry  nerve,  a  nerve  which  carries  impressions  from  the  cells  to 

the  spinal  cord  or  to  the  brain. 

Sew'er,  an  underground  tunnel  which  carries  away  slops  from  houses. 
Skel'e-ton,  the  bones  of  the  body. 
Skull,  the  bony  structure  of  the  head. 
Spi'nal  cord,  the  nervous  cord  inside  the  backbone.      It  gives   off 

nerves,  sends  reflex  orders  to  the  cells,  and  conducts  impulses  to 

and  from  the  brain. 
Starch,  a  food  substance  found  in  nearly  all  kinds  of  vegetable  food. 

Corn  starch  and  common  laundry  starch  a*re  two  kinds. 
Stim'u-lant,  from  a  Latin  word  meaning  a  whip ;  a  substance  which, 

like  a  whip,  compels  the  cells  to  act,  but  does  not  furnish  them  with 

the  power  to  act. 

Stom'ach,  the  muscular  bag  into  which  food  enters  when  it  is  swal- 
lowed. 
Su'gar,  a  sweet  vegetable  food  substance.     There  are  many  different 

forms,  but  during  digestion  all  become  changed  to  the  kind  of  sugar 

found  in  the  grape. 

Sweat,  the  fluid  produced  by  the  skin ;  the  perspiration. 
Sym-pa-thet'ic  sys'tem,  the  collection  of  nerve  cells  and  nerves  which 

send  orders  to  the  muscles  of  the  arteries,  stomach,  intestine,  and 

heart. 
Syn'o'vi-a,  a  fluid  like  the  white  of  an  egg,  which  is  found  inside  of 

joints. 


1 82  GLOSSARY 

T. 

Tar'sal  bones,  the  short  bones  in  the  hinder  half  of  the  foot. 
Tears,  the  saltish  liquid  which  runs  over  the  eyeball. 
Ten'don,  a  strong  cord  connecting  a  muscle  with  a  part  to  be  moved. 
Tho-rac'ic  duct,  a  tube  like  a  goose  quill,  which  extends  up  the  front 

side  of  the  backbone,  and  carries  the  lymph  to  the  blood. 
Tho'rax,  the  part  of  the  inside  of  the  body  which  is  covered  with  ribs. 
Tib'i-a,  the  shin  bone,  extending  from  the  knee  to  the  ankle. 
To-bac'co,  a  narcotic  plant  used  in  smoking  and  chewing,  and  as  snuff. 

U. 

Ul'na,  the  bone  extending  from  the  elbow  to  the  wrist  upon  the  little 

finger  side  of  the  arm. 
U're-a,  the  solid  waste  of  the  body.     It  is  the  ashes  of  albumin,  and  is 

taken  from  the  blood  by  the  kidneys  and  skin. 

V. 

Vein  (vane),  a  tube  carrying  blood  away  from  the  cells  and  back  toward 

the  heart. 

Ven-ti-la'tion,  replacing  the  impure  air  of  a  room  with  pure  air. 
Ven'tri-cle,  one  of  the  thick  lower  pockets  of  the  heart. 
Vil'lus,  one  of  the  tiny  fingers  which  project  into  the  intestine  from  its 

mucous  membrane. 
Vo'cal  cords,  the  bands  in  the  larynx,  which  are  set  in  motion  by  air 

to  form  the  voice. 

Y. 

Yeast,  microscopic  plants,  each  made  of  only  a  single  cell.  By  their 
growth  they  form  alcohol  and  a  gas.  In  making  bread,  the  gas 
bubbles  through  the  dough  and  puffs  up  the  loaf  until  it  is  light. 
Yeast  cakes  are  a  kind  of  dried  bread  dough. 


INDEX 


Abdomen,  21. 
Abscess,  75. 
Achilles,  tendon  of,  167. 
Adam's  apple,  88. 
Air,  u,  83,  92. 
Albumin,  9,  22,  26,  61. 
Alcohol,  50. 
Alcohol  and  arteries,  69. 

blood,  68. 

candy,  140. 

character,  134. 
,        cooking,  139. 

digestion,  52. 

eyes,  147. 

feeling,  133. 

healing,  78. 

heart,  70. 

heat,  102. 

heredity,  135. 

kidneys,  112. 

laws,  54. 

life  insurance,  172. 

liver,  53. 

lungs,  90. 

medicine,  54,  140. 

motion.  133. 

mouth,  51. 

muscles,  170. 

nerves,  132. 


Alcohol  and  nose,  151. 

oxidation,  52,  89. 

skin,  112. 

spinal  cord,  132. 

stomach,  51. 

taste,  152. 

thought,  132. 

treating,  141. 

waste  of  body,  136. 
Ameba,  7,  15,  66. 
Aorta,  63. 
Appetite,  36. 
Arsenic,  42. 
Arterial  blood,  65,  83. 
Artery,  61. 

Artificial  respiration,  87. 
Ashes,  9,  ii. 
Auricle,  63. 


B 


Back  bone,  157. 
Bacteria,  73. 
Baths,  109. 
Beans,  29. 
Bedrooms,  94. 
Beer,  56. 
Bile,  23. 
Biliousness,  24. 
Bitters,  137. 

183 


184 


INDEX 


Bleeding,  61,  72. 
Blister,  105. 
Blood,  15,  60,  65,  83. 
Bone,  155,  161. 
Bowels,  24. 
Brain,  122. 
Brandy,  57. 
Bread,  29. 
Breast  bone,  157. 
Breathing,  81. 
Bright's  disease,  109. 
Bronchi,  80. 
Bunion,  162. 
Burns,  97. 
Butter,  27. 


Callus,  105. 
Capillary,  62,  83. 
Carbolic  acid,  41. 
Carbonic  acid,  u,  83,  108. 
Cartilage,  160. 
Cells,  8,  66,  84,  117,  123. 
Cereals,  29. 
Cerebellum,  122. 
Cerebrum,  122. 
Cheeks,  17. 
Cheese,  27. 
Chest,  81,  157. 
Chewing  gum,  139. 
Chloral,  47. 
Chloroform,  141. 
Chyme,  22. 
Cider,  55. 
Cigarettes,  46. 
Cilia,  81. 
Circulation,  64. 
Clams,  28. 


Clavicle,  159. 
Clot,  61. 

Clothing,  86,  99,  in. 
Coffee,  33,  138. 
Cold  blooded,  101. 
Cold,  taking,  75,  98. 
Cold  feelings,  95. 
Connective  tissue,  8,  66. 
Cooking,  15. 
Corn,  162. 
Corpuscles,  60. 
Cotton,  100. 
Crabs,  28. 
Cream,  27. 
Cross-eyes,  145. 
Cutis,  104. 


Deafness,  149. 
Delirium  tremens,  135, 
Derma,  104. 
Diaphragm,  21,  81. 
Digestion,  15. 
Distillation,  56. 
Dreams,  131. 
Drowning,  88. 
Drugs,  39,  137. 
Drunkenness,  53,  133. 


Ear,  147. 
Eating,  36. 
Eggs,  28. 
Enamel,  17. 
Epidermis,  105. 
Epiglottis,  20. 
Epithelium,  18,  105. 


INDEX 


I8S 


Esophagus,  20. 
Ether,  141. 
Eustachian  tube,  149. 
Exercise,  68,  167. 
Eye,  144. 


Fainting,  68. 
Far  sight,  147. 
Fat,  10,  23,  24,  26,  171. 
Fear,  130. 
Femur,  158. 
Fermentation,  49. 
Fever,  96. 
Fibula,  158. 
Filter,  33. 
Fire  drill,  130. 
Fish,  28. 

Food,  11,  13,  26,  31,  41- 
Foot,  159. 
Frost  bites,  98. 
Fruit,  29. 
Fur,  100. 


Ganglion,  1 19. 
Gastric  juice,  21. 
Gelatine,  9. 
Glands,  18,  21,  108. 
Goose  flesh,  107. 
Gray  matter,  117,  123. 
Gymnasium,  170. 


H 


Habit,  128. 
Hair,  106. 


Hand,  159. 

Hangnail,  106. 

Healing,  71,  75. 

Hearing,  124,  148. 

Heart,  63. 

Heat,  95,  99,  144. 

Heredity,  129. 

Hip,  158. 

History  of  strong  drink,  57. 

Humerus,  159. 

Hydrochloric  acid,  21. 


Inflammation,  74. 
Insect  stings,  42. 
Inspiration,  81. 
Instep,  158. 
Intemperance,  35. 
Intestinal  juice,  22. 
Intestine,  22. 
Iris,  144. 


Jaws,  17. 
Joint,  156,  1 60. 


Kidney,  109. 


Lacteal,  24. 
Larynx,  88. 
Laudanum,  41. 
Lens,  145. 
Ligaments,  160. 


1 86 


INDEX 


Lime,  II. 
Liver,  23. 
Lung,  80. 
Lymph,  66. 
Lymphatics,  67. 
Lymph  nodes,  67. 


M 

Malt,  56. 
Marrow,  155. 
Meat,  28. 
Medulla,  122. 
Memory,  124. 
Milk,  27. 
Mind,  8,  131. 
Minerals,  n,  25. 
Morphine,  41,  47. 
Motion  and  brain,  124. 
Mouth  breathing,  85. 
Mucous  membrane,  18. 
Mucus,  18. 
Muscle,  28,  166. 


N 

Nail,  105. 
Narcotics,  44. 
Near  sight,  147. 
Nerves,  114,  166. 
Nervousness,  129. 
Nicotine,  44. 
Night  air,  94. 
Nitrogen,  83- 
Nose,  150. 
Nuts,  30. 


Oleomargarine,  31. 

Opium,  41,  47- 

Oxidation,    11,   84,  95,   101.   108, 

168. 

Oxygen,  11,83,92. 
Oysters,  28. 


Pain,  74,  116,  143. 
Pancreas,  22. 
Papilla,  104. 
Paregoric,  41. 
Pelvis,  158. 
Pepsin,  21. 
Peptone,  22,  24. 
Periosteum,  156. 
Perspiration,  96,  108. 
Pharynx,  19. 
Plasma,  61 . 
Poisons,  40. 
Potash,  n. 
Potatoes,  29. 
Pulse,  66. 
Pupil,  144. 
Pus,  75. 


Radius,  159. 

Red  blood  cells,  60,  83. 

Reflex  acts,  118. 

Respiration,  80. 

Ribs,  157. 

Root  beer,  56. 


INDEX 


187 


Saliva,  19. 

Salt,  ii,  30, 

Scapula,  159. 

Scar,  75. 

Sensation,  116. 

Senses,  124,  143. 

Serum,  61. 

Sewer,  in. 

Shinbone,  158. 

Shortness  of  breath,  85. 

Shoulder  blade,  159. 

Sickness,  39,  78,  94. 

Sight,  124,  144. 

Skin,  104. 

Skull,  157. 

Sleep,  127. 

Slops,  in. 

Smelling,  124,  150. 

Smoking,  46. 

Snake  bites,  42. 

Snuff,  47. 

Sound,  148. 

Speech,  126. 

Spices,  30. 

Spinal  cord,  117. 

Spine,  157. 

Sprain,  161. 

Starch,  10,  19. 

Stimulant,  34. 

Stomach,  20. 

Sugar,  9,  10,  19,  24,  26. 

Sunstroke,  97. 

Swallowing,  20. 

Sweat,  it>8. 

Sweetbread,  22. 

Sympathetic  system,  119. 

Synovial  membrane,  160. 


Tarsal  bones,  158. 
Tartar,  17. 
Taste,  124,  151. 
Tea,  33,  138. 
Tears,  146. 
Teeth,  16. 

Temperature  sense,  144. 
Tendon,  164. 
Thinking,  125. 
Thoracic  duct,  67. 
Thorax,  81. 
Tibia,  158. 
Tobacco,  39,  44,  91. 
Tobacco  and  brain,  138. 

digestion,  45. 

drink,  138. 

eyes,  147. 

heart,  70. 

lungs,  90. 

mouth,  45. 

muscles,  170. 

smell,  151. 

taste,  152. 

teeth,  17. 
Tongue,  17. 
Touch,  124,  143. 


U 


Ulna,  159. 
Urea,  108. 


Vegetables,  29. 

Vein,  63. 

Venous  blood,  65,  84. 


188 


INDEX 


Ventilation.  93. 
Ventricle,  63. 
Villi,  23. 
Vinegar,  49. 
Vocal  cords,  88. 
Voice,  88. 


W 


Waste  of  body,  108. 
Water,  9,  u,  25,  26,  32,  108. 
Wells,  32,  in. 


Whisky,  57. 

White  blood  cells,  60. 

White  matter,  117,  123. 

Windpipe,  80. 

Wine,  55. 

Worry,  128. 

Woolen,  100. 


Yeast,  49. 


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